[clang-format] clang-format off/on not respected when using C Style comments

Summary:
If the clang-format on/off is in a /* comment */ then the sorting of headers is not ignored

PR40901 - https://bugs.llvm.org/show_bug.cgi?id=40901

Reviewers: djasper, klimek, JonasToth, krasimir, alexfh

Reviewed By: alexfh

Subscribers: alexfh, cfe-commits, llvm-commits

Tags: #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D58819

llvm-svn: 355266