[change-namespace] do not fix calls to overloaded operator functions.

Summary: Also make sure one function reference is only processed once.

Reviewers: hokein

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D27982

llvm-svn: 290176
GitOrigin-RevId: e3f35e4db67f08c14521fc1e4e8f360260bf34bb
3 files changed