[cpp] Suppress -Wextra-semi

Bug: 56257
Change-Id: I28e1e4500d366e94f91c003008889ae5c0347642
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/glog/+/600647
Reviewed-by: Tamir Duberstein <tamird@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index 4c1642c..34eebe6 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -43,6 +43,7 @@
     "src/utilities.cc",
     "src/vlog_is_on.cc",
   ]
+  cflags = [ "-Wno-extra-semi" ]
   public_configs = [ ":glog_config" ]
   deps = [ "//third_party/gflags" ]