[libclang] Bury dead TemporaryFiles

Summary:
AllocatedCXCodeCompleteResults::TemporaryFiles have turned into zombies.
Seven years ago they used to do their job during [[ https://github.com/llvm-mirror/clang/commit/313e26c4e81f0e467490a530548450f4c824a6c4/tools/CIndex/CIndexCodeCompletion.cpp#diff-02d3e692ad507b10af9458b775c5750bL261 | file remapping]], but now they are created just to be torn down in the destructor.

Reviewers: bkramer

Reviewed By: bkramer

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D31288

llvm-svn: 298697