Revert "lit.py: Add new %{shared_output(LABEL)} substitution"

This reverts r315697 and my ill-fated attempts to fix it on Windows.
I'll try again when I get access to a Windows machine.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315793 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed