Attempt to remove linker workaround on the buildbots.

I have no idea if this is still needed, but removing the
workaround seems like the easiest way to test.

I'll revert this change if the bots go red.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@373650 91177308-0d34-0410-b5e6-96231b3b80d8