GN: Add common header extensions

GN now recognizes most common header file extensions:
*.h, *.hh, *.hpp, *.hxx

These are all used inside the chromium repository.
This change makes "gn check" more robust.

R=brettw@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/1933323002
Cr-Original-Commit-Position: refs/heads/master@{#391056}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: cc00b4093699e76fb09489ede68c1eb3fb4b0db7
1 file changed
tree: 373e9e10c8b0ac20b2f92a6d999ab8cb5f98768b
  1. tools/