disable warnings in ANGLE

We already actively don't turn on more warnings; this disables what must
be default warnings.  This is the same logic we apply in our usual
third_party() template (see third_party/third_party.gni).

Change-Id: Icc164f8d288005baf1f0a1c7d408054acc7d4701
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/260881
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

third_party/angle2/BUILD.gn

@@ -57,15 +57,12 @@ config("common") {
 
     # Allow noexcept, even though we build without exceptions
     cflags_cc += [ "/wd4577" ]
-    if (is_clang) {
-      cflags_cc += [
-        # utilities.cpp includes an 'unsigned long' <= UINT_MAX check
-        "-Wno-tautological-constant-compare",
 
-        # With distributed Windows builds, files may lose their case during copy, causing
-        # case-sensitivity mismatch on remote machines.
-        "-Wno-nonportable-include-path",
-      ]
+    # Warnings are just noise if we're not maintaining the code.
+    if (is_win) {
+      cflags = [ "/w" ]
+    } else {
+      cflags = [ "-w" ]
     }
   }
 }