Revert "PR21408: Workaround the appearance of duplicate variables due to...

Revert "PR21408: Workaround the appearance of duplicate variables due to problems when inlining two calls to the same function from the same call site."

The underlying bug has been fixed in r226736 so there's no need to
workaround this anymore.

This reverts commit r220923.

llvm-svn: 226842