[LTO] Fix common test to reflect r279911 and move to X86 subdirectory

Adjust the test to reflect the changes to common handling in r279911.
This test wasn't running due to an incorrect REQUIRES and thus missed
being modified for r279911 before. It was changed to XFAIL when the
bad REQUIRES was discovered.

Remove the XFAIL and move to a new X86 subdirectory that will properly
disable on non-X86.

llvm-svn: 280256