AsmPrinter: Get rid of llvm$workaround$fake$stub$

We currently emit labels with the prefix Lllvm$workaround$fake$stub$ if
the target's MCAsmInfo has getLinkOnceDirective() mapped to something
interesting.  This was apparently a work around introduced in r31033 for
binutils that we don't need anymore.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189187 91177308-0d34-0410-b5e6-96231b3b80d8