PowerPC paranioa testing of symbol merging involving comdat groups

Ensures we don't mistreat st_other localentry bits.

	* testsuite/ld-powerpc/group1.d,
	* testsuite/ld-powerpc/group1.s,
	* testsuite/ld-powerpc/group1.sym,
	* testsuite/ld-powerpc/group2.d,
	* testsuite/ld-powerpc/group2.s,
	* testsuite/ld-powerpc/group2.sym,
	* testsuite/ld-powerpc/group3.s,
	* testsuite/ld-powerpc/group3.sym: New test files.
	* testsuite/ld-powerpc/powerpc.exp: Run new tests.