Add support for EXT_YUV_target

Add new sampler type "__samplerExternal2DY2YEXT"
to sample a YUV texture image and output color value
without any color conversion,
new additional type to specify color space standard formula and
built-in functions for yuv to rgb transformation.

Change-Id: I1780650fe84cd75191c1ca1e4118e89d585bfd92
Reviewed-on: https://chromium-review.googlesource.com/454697
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/compiler/translator/ValidateOutputs.h b/src/compiler/translator/ValidateOutputs.h
index 152d475..c9282d2 100644
--- a/src/compiler/translator/ValidateOutputs.h
+++ b/src/compiler/translator/ValidateOutputs.h
@@ -29,10 +29,12 @@
   private:
     int mMaxDrawBuffers;
     bool mAllowUnspecifiedOutputLocationResolution;
+    bool mUsesFragDepth;
 
     typedef std::vector<TIntermSymbol *> OutputVector;
     OutputVector mOutputs;
     OutputVector mUnspecifiedLocationOutputs;
+    OutputVector mYuvOutputs;
     std::set<std::string> mVisitedSymbols;
 };