Add build files for a MacOS CI build.

PiperOrigin-RevId: 493414473

.bazelrc

diff --git a/.bazelrc b/.bazelrc
index 4748ed8..dda6d24 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -6,3 +6,6 @@
 
 # Don't fail on converting "0xff" to char
 build --copt=-Wno-narrowing
+
+# There is no system ICU on non-Linux platforms
+build:macos --@com_google_googleurl//build_config:system_icu=0