Testsuite: Ensure pie is disabled on some tests

Testsuite: Ensure pie is disabled on some tests

[ Backport of master commit 968aa7ae38. ]

Recent versions of Ubuntu and Debian default GCC to enable pie.

In dump.exp, pie will causes addresses to be out of range for IHEX.

In break-interp.exp, pie is explicitly set for some tests and assumed
to be disabled for the remainder.

Ensure pie is disabled for these tests when required.

In addition, add a pie option to gdb_compile to match the nopie option
and simplify use.

gdb/testsuite/ChangeLog:

	* README: Add pie options.
	* gdb.base/break-interp.exp: Ensure pie is disabled.
	* gdb.base/dump.exp: Likewise.
	* lib/gdb.exp (gdb_compile): Add pie option.