Use `pkg-config` to find GoogleTest and Benchmark.

The GNU make CI workflow is currently broken on macOS because the Homebrew
prefix differs between X64 and ARM64. It turns out that the compiler can't
find GoogleTest (and Benchmark) anymore via the default path(s). We should
really have been specifying the path(s) explicitly long before now anyway.

Change-Id: If526389aa89b20b64ccfcc486769050c351e759f
Reviewed-on: https://code-review.googlesource.com/c/re2/+/63030
Reviewed-by: Paul Wankadia <junyer@google.com>
Reviewed-by: Alex Chernyakhovsky <achernya@google.com>
1 file changed