Merging r354505:

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r354505 | ibiryukov | 2019-02-20 20:08:06 +0100 (Wed, 20 Feb 2019) | 13 lines

[clangd] Store index in '.clangd/index' instead of '.clangd-index'

Summary: To take up the .clangd folder for other potential uses in the future.

Reviewers: kadircet, sammccall

Reviewed By: kadircet

Subscribers: ioeric, MaskRay, jkorous, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58440
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llvm-svn: 354981