MIPS/LD/testsuite: Correct PR ld/22649 test case failures

MIPS/LD/testsuite: Correct PR ld/22649 test case failures

Fix commit d664fd41e15f ("Ignore dynamic references on forced local
symbols") and use alternative test actions and match patterns to
correctly handle messages like:

.../ld/ld-new: Removing unused section '.reginfo' in file 'tmpdir/pr22649-2b.o'

or:

.../ld/ld-new: Removing unused section '.MIPS.options' in file 'tmpdir/pr22649-2b.o'

produced by LD on MIPS targets, removing:

FAIL: Build pr22649-2c.so
FAIL: Build pr22649-2d.so

test suite failures and tightening checks made with `pr22649-2a.so' and
`pr22649-2b.so' test cases.

Keep the original empty action with `pr22649-2c.so' and `pr22649-2d.so'
links and MIPS/ELF targets though, because for them the linker does not
garbage-collect the `.reginfo' section.  This is because the section has
its flags set differently by code in GAS in `md_begin':

    if (strncmp (TARGET_OS, "elf", 3) != 0)
      flags |= SEC_ALLOC | SEC_LOAD;

and consequently BFD linker code in `_bfd_elf_gc_mark_extra_sections':

	  else if (((isec->flags & SEC_DEBUGGING) != 0
		    || (isec->flags & (SEC_ALLOC | SEC_LOAD | SEC_RELOC)) == 0)
		   && elf_next_in_group (isec) == NULL)
	    isec->gc_mark = 1;

marks these sections to be kept due to their SEC_ALLOC, SEC_LOAD and
SEC_RELOC flags all being zero (`.reginfo' sections never have
relocations attached).

	ld/
	PR ld/22649
	* testsuite/ld-elf/pr22649-2ab-mips.msg: New stderr output.
	* testsuite/ld-elf/pr22649-2cd-mips.msg: New stderr output.
	* testsuite/ld-elf/shared.exp: Use the new outputs with
	`mips*-*-*' targets.