Roll src/third_party/re2/src/ a8176127e..30cad2671 (6 commits)

https://chromium.googlesource.com/external/github.com/google/re2.git/+log/a8176127eebc..30cad267151f

$ git log a8176127e..30cad2671 --date=short --no-merges --format='%ad %ae %s'
2019-01-31 junyer Clarify the scope of a comment.
2019-01-31 junyer Work around a bug in older versions of bash. :/
2019-01-31 junyer Refactor the CMake scripts.
2019-01-31 junyer Use bash on Windows since Kokoro offers it.
2019-01-31 junyer Refactor the Bazel scripts.
2019-01-29 junyer Try using bash on Windows since Kokoro offers it.

Created with:
  roll-dep src/third_party/re2/src

R=thakis@chromium.org

Change-Id: I1e616911ebd8b1bcbca4c8a019b6819bf41c699d
Reviewed-on: https://chromium-review.googlesource.com/c/1462154Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630653}

DEPS

@@ -1156,7 +1156,7 @@ deps = {
   },
 
   'src/third_party/re2/src':
-    Var('chromium_git') + '/external/github.com/google/re2.git' + '@' + 'a8176127eebcfef98db8ef9a22d1fa708b196e7c',
+    Var('chromium_git') + '/external/github.com/google/re2.git' + '@' + '30cad267151fa8f1b17da8c1ef0571da6da9a8f1',
 
   'src/third_party/r8': {
       'packages': [