Correct invalid assumptions made by (mostly) DWARF-2 tests

Correct invalid assumptions made by (mostly) DWARF-2 tests

Address issues triggered by the MIPS ISA bit handling change, usually in
tests that make artificial DWARF-2 records:

* gdb.cp/expand-psymtabs-cxx.exp -- this test is debugging an object file
  and assuming addresses will be 0; with the ISA bit set code addresses
  are 1 instead:

(gdb) PASS: gdb.cp/expand-psymtabs-cxx.exp: set language c++
p 'method(long)'
$1 = {void (long)} 0x1 <method(long)>
(gdb) FAIL: gdb.cp/expand-psymtabs-cxx.exp: before expand
p method
$2 = {void (long)} 0x1 <method(long)>
(gdb) FAIL: gdb.cp/expand-psymtabs-cxx.exp: force expand
p 'method(long)'
$3 = {void (long)} 0x1 <method(long)>
(gdb) FAIL: gdb.cp/expand-psymtabs-cxx.exp: after expand

  Fix by matching any hex number, there's no value AFAICT for the test
  in matching 0 exactly, and I suppose the method's offset within
  section can be non-zero for some other reasons on other targets too.

* gdb.cp/nsalias.exp -- this assumes instructions can be aligned
  arbitrarily and places code labels at odd addreses, setting the ISA
  bit and wreaking havoc:

(gdb) PASS: gdb.cp/nsalias.exp: print outer::inner::innermost::x
list outer::inner::innermost::foo
Function "outer::inner::innermost::foo" not defined.
(gdb) FAIL: gdb.cp/nsalias.exp: list outer::inner::innermost::foo
break *outer::inner::innermost::foo
No symbol "foo" in namespace "outer::inner::innermost".
(gdb) FAIL: gdb.cp/nsalias.exp: setting breakpoint at
*outer::inner::innermost::foo
delete $bpnum
No breakpoint number 6.
(gdb) FAIL: gdb.cp/nsalias.exp: (outer::inner::innermost): delete $bpnum

  -- etc., etc...  Fix by aligning labels to 4; required by many
  processors.

* gdb.dwarf2/dw2-canonicalize-type.exp, gdb.dwarf2/dw2-empty-pc-range.exp,
  gdb.dwarf2/pr11465.exp -- these assume an instruction and consequently
  a function can take as little as 1 byte, which makes it impossible to
  look up a code symbol by an address with the ISA bit set as the
  address is already beyond the end of the function:

(gdb) ptype f
No symbol "f" in current context.
(gdb) FAIL: gdb.dwarf2/dw2-canonicalize-type.exp: ptype f

(gdb) PASS: gdb.dwarf2/dw2-empty-pc-range.exp: empty range before CU load
ptype realrange
No symbol "realrange" in current context.
(gdb) FAIL: gdb.dwarf2/dw2-empty-pc-range.exp: valid range after CU load

(gdb) p N::c.C
Cannot take address of method C.
(gdb) FAIL: gdb.dwarf2/pr11465.exp: p N::c.C

  -- fix by increasing the size of the function to 4 (perhaps code in
  gdb/mips-tdep.c could look up code symbols up to twice, with and
  failing that without the ISA bit set, but it seems wrong to me to
  implement specific handling for invalid code just to satisfy test
  cases that assume too much about the target).

* gdb.dwarf2/dw2-case-insensitive.exp -- an artificial code label is
  created, but does not work because data (a `.align' pseudo-op in this
  case) follows and as a result the label has no MIPS16 or microMIPS
  annotation in the symbol table:

(gdb) PASS: gdb.dwarf2/dw2-case-insensitive.exp: set case-sensitive off
info functions fUnC_lang
All functions matching regular expression "fUnC_lang":

File file1.txt:
foo FUNC_lang(void);

Non-debugging symbols:
0x004006e0  FUNC_lang_start
(gdb) FAIL: gdb.dwarf2/dw2-case-insensitive.exp: regexp case-sensitive off

  -- fix by adding a `.insn' pseudo-op on MIPS targets; the pseudo-op
  marks data as instructions.

* gdb.dwarf2/dw2-stack-boundary.exp -- the test case enables complaints
  and assumes none will be issued beyond ones explicitly arranged by the
  test case, however overlapping sections are noticed while minimal
  symbols are looked up by `mips_adjust_dwarf2_addr' in DWARF-2 record
  processing:

(gdb) set complaints 100
(gdb) PASS: gdb.dwarf2/dw2-stack-boundary.exp: set complaints 100
file ./dw2-stack-boundary
Reading symbols from ./dw2-stack-boundary...location description stack
underflow...location description stack overflow...unexpected overlap
between:
 (A) section `.reginfo' from `.../gdb.dwarf2/dw2-stack-boundary' [0x0, 0x18)
 (B) section `*COM*' from `.../gdb.dwarf2/dw2-stack-boundary' [0x0, 0x0).
Will ignore section B...unexpected overlap between:
 (A) section `.reginfo' from `.../gdb.dwarf2/dw2-stack-boundary' [0x0, 0x18)
 (B) section `*UND*' from `.../gdb.dwarf2/dw2-stack-boundary' [0x0, 0x0).
Will ignore section B...unexpected overlap between:
 (A) section `.reginfo' from `.../gdb.dwarf2/dw2-stack-boundary' [0x0, 0x18)
 (B) section `*ABS*' from `.../gdb.dwarf2/dw2-stack-boundary' [0x0, 0x0).
Will ignore section B...done.

(gdb) FAIL: gdb.dwarf2/dw2-stack-boundary.exp: check partial symtab errors

  -- fix by ignoring any extra noise as long as what we look for is
  found.

	* gdb.cp/expand-psymtabs-cxx.exp: Accept any address of
	`method(long)', not just 0x0.
	* gdb.cp/nsalias.exp: Align code labels to 4.
	* gdb.dwarf2/dw2-canonicalize-type.S (main): Expand to 4-bytes.
	* gdb.dwarf2/dw2-empty-pc-range.S (main): Likewise.
	* gdb.dwarf2/pr11465.S (_ZN1N1cE): Likewise.
	* gdb.dwarf2/dw2-case-insensitive.c (START_INSNS): New macro.
	(cu_text_start, FUNC_lang_start): Use `START_INSNS'.
	* gdb.dwarf2/dw2-stack-boundary.exp: Accept noise in complaints.