TexCoords and MultiTexCoords implementations for shaders

Change-Id: I693151e3ea0849eed27d118cf90ff4ef12446e63
Reviewed-on: https://swiftshader-review.googlesource.com/3723
Reviewed-by: Maxime Grégoire <mgregoire@google.com>
Tested-by: Maxime Grégoire <mgregoire@google.com>
7 files changed