This reverts commit r198441.
This change doesn't build on Windows, and doesn't do the right thing on
Linux and other platforms that don't use a _Z prefix instead of __Z for
C++ names.
It also had no tests, so it wasn't clear how to fix it forward.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198445 91177308-0d34-0410-b5e6-96231b3b80d8