Kokoro: Allow 'Fixes:' in bug check
Kokoro: Allow 'Fixes:' in bug check

This adds to 'Bug:', 'Issue:' and 'Regres:' as accepted CL grep checks.

Fixes: b/143093187
Change-Id: Iae44d8e8e49f7534bb940ec977edb4afcddc308e
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/37449
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Kokoro-Presubmit: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Tested-by: Ben Clayton <1f693eb7158dc33015048c09d6712f74dabddf79@google.com>

bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader