[DebugInfo][If-Converter] Update call site info during the optimization

During the If-Converter optimization pay attention when copying or
deleting call instructions in order to keep call site information in
valid state.

Reviewers: aprantl, vsk, efriedma

Reviewed By: vsk, efriedma

Differential Revision: https://reviews.llvm.org/D66955

llvm-svn: 374068