llvm-mc.

This fixes the failing validation of callindirect.pnacl.ll.

The following tests fail to validate (some due to the
addition of -filetype=obj):
 * convert.ll
 * globalinit.pnacl.ll
 * mangle.ll
 * nacl-atomic-fence-all.ll
 * shift.ll

BUG=none
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/410743005