use -isystem for headers from third_party

This supresses warnings from code in those headers,
e.g. warnings about switch case fallthrough in SDL_memset4(),
defined inline in SDL_stdinc.h.

Change-Id: I5341a67d4949b28ec5ffa6b7ae433748406e99db
Reviewed-on: https://skia-review.googlesource.com/109140
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/third_party/third_party.gni b/third_party/third_party.gni
index 7aaf63586f..612958b9b4 100644
--- a/third_party/third_party.gni
+++ b/third_party/third_party.gni
@@ -8,7 +8,14 @@ template("third_party") {
     if (defined(invoker.public_defines)) {
       defines = invoker.public_defines
     }
-    include_dirs = invoker.public_include_dirs
+    if (is_win) {
+        include_dirs = invoker.public_include_dirs
+    } else {
+        cflags = []
+        foreach(dir, invoker.public_include_dirs) {
+            cflags += ["-isystem", rebase_path(dir)]
+        }
+    }
   }
   source_set(target_name) {
     forward_variables_from(invoker, "*", [ "public_include_dirs" ])