Including libyuv headers using fully qualified paths.

Using fully qualified paths to include libyuv headers allows WebRTC to
avoid to rely on the //third_party/libyuv:libyuv_config target to
set the -I compiler flag.

Today some WebRTC targets depend on //third_party/libyuv only to
include //third_party/libyuv:libyuv_config but with fully qualified
paths this should not be needed anymore.

A follow-up CL will remove //third_party/libyuv from some targets that
don't need it because they are not including libyuv headers.

Bug: webrtc:8605
Change-Id: Icec707ca761aaf2ea8088e7f7a05ddde0de2619a
No-Try: True
Reviewed-on: https://webrtc-review.googlesource.com/28220
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Magnus Flodman <mflodman@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21209}

modules/video_processing/DEPS

@@ -2,4 +2,5 @@ include_rules = [
   "+common_audio",
   "+common_video",
   "+system_wrappers",
+  "+third_party/libyuv",
 ]

modules/video_processing/video_denoiser.cc

@@ -8,9 +8,9 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "common_video/libyuv/include/webrtc_libyuv.h"
 #include "modules/video_processing/video_denoiser.h"
-#include "libyuv/planar_functions.h"
+#include "common_video/libyuv/include/webrtc_libyuv.h"
+#include "third_party/libyuv/include/libyuv/planar_functions.h"
 
 namespace webrtc {