Hardcode the list of ELF targets here rather than using a glob.

The code was making non-portable assumptions about the exact string returned by
the glob (possibly by the shell?); this is more robust and matches what is done
everywhere else.


git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@220117 91177308-0d34-0410-b5e6-96231b3b80d8