Add clangd to gitignore

This folder is an output for an experimental
`-background-index` command line argument.

Bug: None
Change-Id: Iaa1db62f54d844d271b2c56a686cdad5117ebe74
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1524392
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641096}
1 file changed