[clang-format] [NFC] Ensure clang-format is itself clang-formatted.

Summary:
Before making a proposed change, ensure ClangFormat.cpp is fully clang-formatted,

no functional change just clang-formatting using the in tree .clang-format.

Reviewers: mitchell-stellar

Reviewed By: mitchell-stellar

Subscribers: Eugene.Zelenko, cfe-commits

Tags: #clang-format, #clang

Differential Revision: https://reviews.llvm.org/D68551

llvm-svn: 373921