Include skia/include/codec directory into skia_config for iOS too

We currently exclude this directory from skia_config iOS simply because
it has not been unused. However, due to modifications to PaintImage to
support YUV decoding, there is header inclusion that leads back to
third_party/skia/include/codec/SkEncodedOrigin.h. This caused a compile
error leading to those YUV changes [1] to be reverted.

[1] crrev.com/c/1368687

Bug: NOBUG
Change-Id: Ie42587226f8f9cfd817f98e6157294deb4427ea0
Reviewed-on: https://chromium-review.googlesource.com/c/1440243Reviewed-by: Leon Scroggins <scroggo@chromium.org>
Commit-Queue: Leon Scroggins <scroggo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#627031}

skia/BUILD.gn

@@ -33,6 +33,7 @@ config("skia_config") {
     "config",
     "ext",
     "//third_party/skia/include/c",
+    "//third_party/skia/include/codec",
     "//third_party/skia/include/config",
     "//third_party/skia/include/core",
     "//third_party/skia/include/docs",
@@ -57,7 +58,6 @@ config("skia_config") {
   ]
 
   if (!is_ios) {
-    include_dirs += [ "//third_party/skia/include/codec" ]
     defines += [ "SK_HAS_JPEG_LIBRARY" ]
   }
   if (enable_vulkan) {