gas: testsuite: add an x86 testsuite for SCFI

gas: testsuite: add an x86 testsuite for SCFI

The testsuite for SCFI contains target-specific tests.

When a test is executed with --scfi=experimental command line option,
the CFI annotations in the test .s files are skipped altogether by the
GAS for processing.  The CFI directives in the input assembly files are,
however, validated by running the assembler one more time without
--scfi=experimental.

Some testcases are used to highlight those asm constructs that the SCFI
machinery in GAS currently does not support:

  - Only System V AMD64 ABI is supported for now. Using either --32 or
    --x32 with SCFI results in hard error.
    See scfi-unsupported-1.s.

  - Untraceable stack-pointer manipulation in function epilougue and prologue.
    See scfi-unsupported-2.s.

  - Using Dynamically Realigned Arguement Pointer (DRAP) register to
    realign the stack.  For SCFI, the CFA must be only REG_SP or REG_FP
    based.  See scfi-unsupported-drap-1.s

Some testcases are used to highlight some diagnostics that the SCFI
machinery in GAS currently issues, with an intent to help user correct
inadvertent errors in their hand-written asm.  An error is issued when
GAS finds that input asm is not amenable to correct CFI synthesis.

  - (#1) "Warning: SCFI: Asymetrical register restore"
  - (#2) "Error: SCFI: usage of REG_FP as scratch not supported"
  - (#3) "Error: SCFI: unsupported stack manipulation pattern"

In case of (#2) and (#3), SCFI generation is skipped for the respective
function.  Above is a subset of the warnings/errors implemented in the
code.

gas/testsuite/:
	* gas/scfi/README: New test.
	* gas/scfi/x86_64/ginsn-add-1.l: New test.
	* gas/scfi/x86_64/ginsn-add-1.s: New test.
	* gas/scfi/x86_64/ginsn-dw2-regnum-1.l: New test.
	* gas/scfi/x86_64/ginsn-dw2-regnum-1.s: New test.
	* gas/scfi/x86_64/ginsn-pop-1.l: New test.
	* gas/scfi/x86_64/ginsn-pop-1.s: New test.
	* gas/scfi/x86_64/ginsn-push-1.l: New test.
	* gas/scfi/x86_64/ginsn-push-1.s: New test.
	* gas/scfi/x86_64/scfi-add-1.d: New test.
	* gas/scfi/x86_64/scfi-add-1.l: New test.
	* gas/scfi/x86_64/scfi-add-1.s: New test.
	* gas/scfi/x86_64/scfi-add-2.d: New test.
	* gas/scfi/x86_64/scfi-add-2.l: New test.
	* gas/scfi/x86_64/scfi-add-2.s: New test.
	* gas/scfi/x86_64/scfi-asm-marker-1.d: New test.
	* gas/scfi/x86_64/scfi-asm-marker-1.l: New test.
	* gas/scfi/x86_64/scfi-asm-marker-1.s: New test.
	* gas/scfi/x86_64/scfi-asm-marker-2.d: New test.
	* gas/scfi/x86_64/scfi-asm-marker-2.l: New test.
	* gas/scfi/x86_64/scfi-asm-marker-2.s: New test.
	* gas/scfi/x86_64/scfi-asm-marker-3.d: New test.
	* gas/scfi/x86_64/scfi-asm-marker-3.l: New test.
	* gas/scfi/x86_64/scfi-asm-marker-3.s: New test.
	* gas/scfi/x86_64/scfi-bp-sp-1.d: New test.
	* gas/scfi/x86_64/scfi-bp-sp-1.l: New test.
	* gas/scfi/x86_64/scfi-bp-sp-1.s: New test.
	* gas/scfi/x86_64/scfi-bp-sp-2.d: New test.
	* gas/scfi/x86_64/scfi-bp-sp-2.l: New test.
	* gas/scfi/x86_64/scfi-bp-sp-2.s: New test.
	* gas/scfi/x86_64/scfi-callee-saved-1.d: New test.
	* gas/scfi/x86_64/scfi-callee-saved-1.l: New test.
	* gas/scfi/x86_64/scfi-callee-saved-1.s: New test.
	* gas/scfi/x86_64/scfi-callee-saved-2.d: New test.
	* gas/scfi/x86_64/scfi-callee-saved-2.l: New test.
	* gas/scfi/x86_64/scfi-callee-saved-2.s: New test.
	* gas/scfi/x86_64/scfi-callee-saved-3.d: New test.
	* gas/scfi/x86_64/scfi-callee-saved-3.l: New test.
	* gas/scfi/x86_64/scfi-callee-saved-3.s: New test.
	* gas/scfi/x86_64/scfi-callee-saved-4.d: New test.
	* gas/scfi/x86_64/scfi-callee-saved-4.l: New test.
	* gas/scfi/x86_64/scfi-callee-saved-4.s: New test.
	* gas/scfi/x86_64/scfi-cfg-1.d: New test.
	* gas/scfi/x86_64/scfi-cfg-1.l: New test.
	* gas/scfi/x86_64/scfi-cfg-1.s: New test.
	* gas/scfi/x86_64/scfi-cfg-2.d: New test.
	* gas/scfi/x86_64/scfi-cfg-2.l: New test.
	* gas/scfi/x86_64/scfi-cfg-2.s: New test.
	* gas/scfi/x86_64/scfi-cfi-label-1.d: New test.
	* gas/scfi/x86_64/scfi-cfi-label-1.l: New test.
	* gas/scfi/x86_64/scfi-cfi-label-1.s: New test.
	* gas/scfi/x86_64/scfi-cfi-sections-1.d: New test.
	* gas/scfi/x86_64/scfi-cfi-sections-1.l: New test.
	* gas/scfi/x86_64/scfi-cfi-sections-1.s: New test.
	* gas/scfi/x86_64/scfi-cofi-1.d: New test.
	* gas/scfi/x86_64/scfi-cofi-1.l: New test.
	* gas/scfi/x86_64/scfi-cofi-1.s: New test.
	* gas/scfi/x86_64/scfi-diag-1.l: New test.
	* gas/scfi/x86_64/scfi-diag-1.s: New test.
	* gas/scfi/x86_64/scfi-diag-2.l: New test.
	* gas/scfi/x86_64/scfi-diag-2.s: New test.
	* gas/scfi/x86_64/scfi-dyn-stack-1.d: New test.
	* gas/scfi/x86_64/scfi-dyn-stack-1.l: New test.
	* gas/scfi/x86_64/scfi-dyn-stack-1.s: New test.
	* gas/scfi/x86_64/scfi-enter-1.d: New test.
	* gas/scfi/x86_64/scfi-enter-1.l: New test.
	* gas/scfi/x86_64/scfi-enter-1.s: New test.
	* gas/scfi/x86_64/scfi-fp-diag-2.l: New test.
	* gas/scfi/x86_64/scfi-fp-diag-2.s: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-1.d: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-1.l: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-1.s: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-2.d: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-2.l: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-2.s: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-3.d: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-3.l: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-3.s: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-4.d: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-4.l: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-4.s: New test.
	* gas/scfi/x86_64/scfi-indirect-mov-5.s: New test.
	* gas/scfi/x86_64/scfi-lea-1.d: New test.
	* gas/scfi/x86_64/scfi-lea-1.l: New test.
	* gas/scfi/x86_64/scfi-lea-1.s: New test.
	* gas/scfi/x86_64/scfi-leave-1.d: New test.
	* gas/scfi/x86_64/scfi-leave-1.l: New test.
	* gas/scfi/x86_64/scfi-leave-1.s: New test.
	* gas/scfi/x86_64/scfi-pushq-1.d: New test.
	* gas/scfi/x86_64/scfi-pushq-1.l: New test.
	* gas/scfi/x86_64/scfi-pushq-1.s: New test.
	* gas/scfi/x86_64/scfi-pushsection-1.d: New test.
	* gas/scfi/x86_64/scfi-pushsection-1.l: New test.
	* gas/scfi/x86_64/scfi-pushsection-1.s: New test.
	* gas/scfi/x86_64/scfi-pushsection-2.d: New test.
	* gas/scfi/x86_64/scfi-pushsection-2.l: New test.
	* gas/scfi/x86_64/scfi-pushsection-2.s: New test.
	* gas/scfi/x86_64/scfi-selfalign-func-1.d: New test.
	* gas/scfi/x86_64/scfi-selfalign-func-1.l: New test.
	* gas/scfi/x86_64/scfi-selfalign-func-1.s: New test.
	* gas/scfi/x86_64/scfi-simple-1.d: New test.
	* gas/scfi/x86_64/scfi-simple-1.l: New test.
	* gas/scfi/x86_64/scfi-simple-1.s: New test.
	* gas/scfi/x86_64/scfi-simple-2.d: New test.
	* gas/scfi/x86_64/scfi-simple-2.l: New test.
	* gas/scfi/x86_64/scfi-simple-2.s: New test.
	* gas/scfi/x86_64/scfi-sub-1.d: New test.
	* gas/scfi/x86_64/scfi-sub-1.l: New test.
	* gas/scfi/x86_64/scfi-sub-1.s: New test.
	* gas/scfi/x86_64/scfi-sub-2.d: New test.
	* gas/scfi/x86_64/scfi-sub-2.l: New test.
	* gas/scfi/x86_64/scfi-sub-2.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-1.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-1.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-2.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-2.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-3.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-3.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-4.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-4.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-cfg-1.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-cfg-1.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-cfg-2.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-cfg-2.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-drap-1.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-drap-1.s: New test.
	* gas/scfi/x86_64/scfi-unsupported-insn-1.l: New test.
	* gas/scfi/x86_64/scfi-unsupported-insn-1.s: New test.
	* gas/scfi/x86_64/scfi-x86-64.exp: New file.