[gold] Fix test accidentally regressed for newer gold

With r279911 I accidentally regressed the gold/X86/start-lib-common.ll
test for newer golds (v1.12+) that honor the --start-lib/--end-lib.
Remove the alignment which should not be there to make this work with
both old and new gold linkers.

Additionally, now that we have a subdirectory for v1.12+ gold tests,
copy this test there and check specifically for the v1.12+ behavior.

llvm-svn: 279977