Fix handling of compiler flags with parameters

`flag_index` was undefined in ProcessIndividualFlag() after the function
had been split off from GetClangOptionsFromCommandLine().

Change-Id: Ibe26b649b916af14db52197cda61e5ec1ca112e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4547703
Reviewed-by: Łukasz Anforowicz <lukasza@chromium.org>
Commit-Queue: Wojciech Dzierżanowski <wdzierzanowski@opera.com>
Reviewed-by: Brian Geffon <bgeffon@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1149575}
NOKEYCHECK=True
GitOrigin-RevId: 76c169d6dd484ef1482b3d1faec7d9dff55ccc1f
1 file changed