Auto merge of #1210 - JerryShih:fix-yuv-color-space-error, r=glennw
Auto merge of #1210 - JerryShih:fix-yuv-color-space-error, r=glennw

Fix the YCbCr color conversion matrix memory layout error and the wrong GL_APPLE_rgb_422 format texture fetching.

r? @kvark @glennw
cc @nical

I try to use the GL_APPLE_rgb_422 with the real video at mac. There are some bugs in that. : (

a) fix the wrong channel fetching for GL_APPLE_rgb_422.
These come from the spec:
> In order to avoid defining entirely new color channels within GL,the Y, Cb and Cr color channels
> within the 422 data are mapped into the existing green, blue and red color channels, respectively.
> Developers must write their own fragment shader/program to perform the desired color space
> transformation.
https://www.khronos.org/registry/OpenGL/extensions/APPLE/APPLE_rgb_422.txt

b) fix the color conversion matrix memory layout.
https://www.opengl.org/archives/resources/faq/technical/transformations.htm

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