Use the given YV12 texture stride instead of computing it from width.

Bug 25690690

Change-Id: If25a8868effb1e55908c4041555e553b52ee789a
Reviewed-on: https://swiftshader-review.googlesource.com/4292
Reviewed-by: Keun Soo Yim <yim@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>

src/Renderer/Sampler.cpp

diff --git a/src/Renderer/Sampler.cpp b/src/Renderer/Sampler.cpp
index 3de645c..aaf6a49 100644
--- a/src/Renderer/Sampler.cpp
+++ b/src/Renderer/Sampler.cpp
@@ -224,7 +224,7 @@
 				   internalTextureFormat == FORMAT_YV12_BT709 ||
 				   internalTextureFormat == FORMAT_YV12_JFIF)
 				{
-					unsigned int YStride = align(width, 16);
+					unsigned int YStride = pitchP;
 					unsigned int YSize = YStride * height;
 					unsigned int CStride = align(YStride / 2, 16);
  					unsigned int CSize = CStride * height / 2;