[config] Suppress implicit fallthrough

Change-Id: Ie2ee85429b4fcfc9e07320bfc53ae6656b3d4bcc
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/c-ares/+/527277
Reviewed-by: Shai Barack <shayba@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index b996874..0aff353 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -10,7 +10,13 @@
 config("cares_config") {
   include_dirs = [ "." ]
   defines = [ "HAVE_CONFIG_H" ]
-  cflags = [ "-Wno-conversion" ]
+}
+
+config("cares_warnings") {
+  cflags = [
+    "-Wno-conversion",
+    "-Wno-implicit-fallthrough",
+  ]
 }
 
 static_library("cares") {
@@ -92,5 +98,6 @@
     "ares_version.h",
   ]
 
+  configs += [ ":cares_warnings" ]
   public_configs = [ ":cares_config" ]
 }