Moved selection of I915 hack out of the YUV shader.

client/deps/glbench/src/yuv2rgb_2.glslf

 /*
  * Copyright 2010, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 17 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 /*
  * This is an optimized version of the YUV to RGB conversion shader.  This
  * shader assumes the height of U and V planes is odd, which means the height
  * of the original image is 2 modulo 4.
  */
 
-#define I915_WORKAROUND 1
-
 uniform sampler2D textureSampler;
 uniform sampler2D paritySampler;
 
 varying vec2 lineCounter;
 varying vec2 yPlane;
 varying vec2 uPlane;
 varying vec2 vPlane;
 
 void main() {
   /*
    * If the height of the original image is even, offset_odd is not needed.
    */
-#if I915_WORKAROUND
+#if defined(I915_WORKAROUND)
   vec2 offset_even = vec2(texture2D(paritySampler, gl_TexCoord[0].xy).x * 0.5,
                           0.0);
 #else
   vec2 offset_even = vec2(texture2D(paritySampler, lineCounter).x * 0.5, 0.0);
 #endif
   vec2 offset_odd = vec2(0.5 - offset_even.x, 0.0);
 
-#if I915_WORKAROUND
+#if defined(I915_WORKAROUND)
   float yChannel = texture2D(textureSampler, gl_TexCoord[0].zw).x;
   float uChannel = texture2D(textureSampler, gl_TexCoord[1].xy + offset_even).x;
   float vChannel = texture2D(textureSampler, gl_TexCoord[1].zw + offset_odd).x;
 #else
   float yChannel = texture2D(textureSampler, yPlane).x;
   float uChannel = texture2D(textureSampler, uPlane + offset_even).x;
   float vChannel = texture2D(textureSampler, vPlane + offset_odd).x;
 #endif
   /*
    * This does the colorspace conversion from Y'UV to RGB as a matrix
    * multiply.  It also does the offset of the U and V channels from
    * [0,1] to [-.5,.5] as part of the transform.
    */
   vec4 channels = vec4(yChannel, uChannel, vChannel, 1.0);
   mat4 conversion = mat4( 1.0,    1.0,    1.0,   0.0,
                           0.0,   -0.344,  1.772, 0.0,
                           1.402, -0.714,  0.0,   0.0,
                          -0.701,  0.529, -0.886, 1.0);
 
   gl_FragColor = conversion * channels;
 }