Accept mips-sgi-irix output in a few ld tests

Accept mips-sgi-irix output in a few ld tests

mips-sgi-irix gas emits STT_OBJECT symbols where other assemblers
would use STT_NOTYPE.  See mips_frob_symbol in gas/config/tc-mips.c.
Also, the section of some dynamic symbols is set to SHN_MIPS_TEXT or
SHN_MIPS_DATA.  See _bfd_mips_elf_finish_dynamic_symbol in
bfd/elfxx-mips.c.  These differences are visible in readelf output
and cause some tests to fail for no other good reason.

The patch fixes the following fails and removes an xfail.
FAIL: ld-elf/pr23591
FAIL: PROVIDE_HIDDEN test (auxiliary shared object)
FAIL: PR ld/21233 dynamic symbols with section GC (auxiliary shared library)

	* testsuite/ld-elf/pr21233-l.sd: Accept OBJECT for type and
	PRC for section of symbols.
	* testsuite/ld-elf/pr23591.d: Likewise.
	* testsuite/ld-elf/provide-hidden-s.nd: Likewise.
	* testsuite/ld-mips-elf/start.s: Make symbols function type.
	* testsuite/ld-mips-elf/hash2.d: Adjust.  Don't xfail irix.