Suppress deprecation warnings

Change-Id: Iaa9a39159261990da8718dcbb205557424ab733a
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/grpc/+/563403
Reviewed-by: James Robinson <jamesr@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index fd16e2c..27d74b5 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -18,6 +18,10 @@
     "GRPC_USE_PROTO_LITE",
     "GPR_SUPPORT_CHANNELS_FROM_FD",
   ]
+
+  # TODO(https://fxbug.dev/68325): Remove this when grpc is updated past
+  # https://github.com/grpc/grpc/commit/de76cf8.
+  cflags = [ "-Wno-deprecated-declarations" ]
 }
 
 config("grpc_warnings") {