Fix minor cppcheck-found issues

src/utils/SkBitSet.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkBitSet.h"
 
 SkBitSet::SkBitSet(int numberOfBits)
     : fBitData(NULL), fDwordCount(0), fBitCount(numberOfBits) {
     SkASSERT(numberOfBits > 0);
     // Round up size to 32-bit boundary.
     fDwordCount = (numberOfBits + 31) / 32;
     fBitData.set(malloc(fDwordCount * sizeof(uint32_t)));
     clearAll();
 }
 
 SkBitSet::SkBitSet(const SkBitSet& source)
     : fBitData(NULL), fDwordCount(0), fBitCount(0) {
     *this = source;
 }
 
-const SkBitSet& SkBitSet::operator=(const SkBitSet& rhs) {
+SkBitSet& SkBitSet::operator=(const SkBitSet& rhs) {
     if (this == &rhs) {
         return *this;
     }
     fBitCount = rhs.fBitCount;
     fBitData.free();
     fDwordCount = rhs.fDwordCount;
     fBitData.set(malloc(fDwordCount * sizeof(uint32_t)));
     memcpy(fBitData.get(), rhs.fBitData.get(), fDwordCount * sizeof(uint32_t));
     return *this;
 }
@@ skipping 37 matching lines @@
     if (fBitCount != source.fBitCount) {
         return false;
     }
     uint32_t* targetBitmap = internalGet(0);
     uint32_t* sourceBitmap = source.internalGet(0);
     for (size_t i = 0; i < fDwordCount; ++i) {
         targetBitmap[i] |= sourceBitmap[i];
     }
     return true;
 }