Use RE2 for the regex implementation when building with Bazel and using Abseil

bazel build --define=absl=1 ...

A dependency on RE2 is now required when building GoogleTest with Abseil.
Using RE2 will provide a consistent cross-platform regex experience.

Users will need to add the com_googlesource_code_re2, bazel_skylib,
and platforms repository to their WORKSPACE files. See our WORKSPACE
file in the root directory of this project for an example of how to
add the dependencies.

Please note that the com_googlesource_code_re2 dependency must use a
commit from the `abseil` branch of the project:
https://github.com/google/re2/tree/abseil

PiperOrigin-RevId: 444650118
Change-Id: I45c55b26684c0c50d721a05b81c5f8a0c092400f

WORKSPACE

@@ -4,9 +4,18 @@ load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 http_archive(
     name = "com_google_absl",
-    sha256 = "93451aaccbf6a9618df7182fdf9ecf281284d6418a0d66eff33ae0cf05eba417",
-    strip_prefix = "abseil-cpp-ec33f404bb16564a9aea3044cd8504d6885165b0",
-    urls = ["https://github.com/abseil/abseil-cpp/archive/ec33f404bb16564a9aea3044cd8504d6885165b0.zip"],  # 2022-03-03T14:43:16Z
+    sha256 = "f88c0030547281e8283ff183db61564ff08d3322a8c2e2de4c40e38c03c69aea",
+    strip_prefix = "abseil-cpp-c27ab06897f330267bed99061ed3e523e2606bf1",
+    urls = ["https://github.com/abseil/abseil-cpp/archive/c27ab06897f330267bed99061ed3e523e2606bf1.zip"],  # 2022-04-18T19:51:27Z
+)
+
+# Note this must use a commit from the `abseil` branch of the RE2 project.
+# https://github.com/google/re2/tree/abseil
+http_archive(
+    name = "com_googlesource_code_re2",
+    sha256 = "906d0df8ff48f8d3a00a808827f009a840190f404559f649cb8e4d7143255ef9",
+    strip_prefix = "re2-a276a8c738735a0fe45a6ee590fe2df69bcf4502",
+    urls = ["https://github.com/google/re2/archive/a276a8c738735a0fe45a6ee590fe2df69bcf4502.zip"],  # 2022-04-08
 )
 
 http_archive(
@@ -15,3 +24,16 @@ http_archive(
     strip_prefix = "rules_python-ed6cc8f2c3692a6a7f013ff8bc185ba77eb9b4d2",
     urls = ["https://github.com/bazelbuild/rules_python/archive/ed6cc8f2c3692a6a7f013ff8bc185ba77eb9b4d2.zip"],  # 2021-05-17T00:24:16Z
 )
+
+http_archive(
+    name = "bazel_skylib",
+    urls = ["https://github.com/bazelbuild/bazel-skylib/releases/download/1.2.1/bazel-skylib-1.2.1.tar.gz"],
+    sha256 = "f7be3474d42aae265405a592bb7da8e171919d74c16f082a5457840f06054728",
+)
+
+http_archive(
+    name = "platforms",
+    sha256 = "b601beaf841244de5c5a50d2b2eddd34839788000fa1be4260ce6603ca0d8eb7",
+    strip_prefix = "platforms-98939346da932eef0b54cf808622f5bb0928f00b",
+    urls = ["https://github.com/bazelbuild/platforms/archive/98939346da932eef0b54cf808622f5bb0928f00b.zip"],
+)