[bazel] Add third_party to skia_all_hdrs

No-Try: true
Change-Id: I15d274bb7c63a3ddfd1d9143b472454cffcf0644
Reviewed-on: https://skia-review.googlesource.com/99541
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
diff --git a/public.bzl b/public.bzl
index 1e28940..4eaecf8 100644
--- a/public.bzl
+++ b/public.bzl
@@ -55,7 +55,11 @@
 ## skia_{all,public}_hdrs()
 ################################################################################
 def skia_all_hdrs():
-  return native.glob(["src/**/*.h", "include/**/*.h"])
+  return native.glob([
+      "src/**/*.h",
+      "include/**/*.h",
+      "third_party/**/*.h",
+  ])
 
 def skia_public_hdrs():
   return native.glob(["include/**/*.h"],