Fix uninit texture key with odd number of textures

src/gpu/gl/GrGLProgramDesc.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "GrGLProgramDesc.h"
 
 #include "GrProcessor.h"
 #include "GrGLGpu.h"
@@ skipping 12 matching lines @@
         return;
     }
     uint16_t* k16 = SkTCast<uint16_t*>(b->add32n(word32Count));
     for (int i = 0; i < numTextures; ++i) {
         const GrTextureAccess& access = proc.textureAccess(i);
         bool isExternal = (GR_GL_TEXTURE_EXTERNAL ==
                            static_cast<GrGLTexture*>(access.getTexture())->target());
         k16[i] = caps.configTextureSwizzle(access.getTexture()->config()).asKey() |
                  (isExternal ? 0xFF00 : 0x0000);
     }
+    // zero the last 16 bits if the number of textures is odd.
+    if (numTextures & 0x1) {
+        k16[numTextures] = 0;
+    }
 }
 
 /**
  * A function which emits a meta key into the key builder.  This is required because shader code may
  * be dependent on properties of the effect that the effect itself doesn't use
  * in its key (e.g. the pixel format of textures used). So we create a meta-key for
  * every effect using this function. It is also responsible for inserting the effect's class ID
  * which must be different for every GrProcessor subclass. It can fail if an effect uses too many
  * transforms, etc, for the space allotted in the meta-key.  NOTE, both FPs and GPs share this
  * function because it is hairy, though FPs do not have attribs, and GPs do not have transforms
@@ skipping 97 matching lines @@
     } else {
         header->fIgnoresCoverage = 0;
     }
 
     header->fSnapVerticesToPixelCenters = pipeline.snapVerticesToPixelCenters();
     header->fColorEffectCnt = pipeline.numColorFragmentProcessors();
     header->fCoverageEffectCnt = pipeline.numCoverageFragmentProcessors();
     glDesc->finalize();
     return true;
 }