Merging r366541:

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r366541 | hokein | 2019-07-19 10:33:39 +0200 (Fri, 19 Jul 2019) | 11 lines

[clangd] cleanup: unify the implemenation of checking a location is inside main file.

Summary: We have variant implementations in the codebase, this patch unifies them.

Reviewers: ilya-biryukov, kadircet

Subscribers: MaskRay, jkorous, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64915
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llvm-svn: 368669