Fix several ineffective integer overflow checks

Commit edd4a76 (which addressed bugs 15328708, 15342615, 15342751) added
several integer overflow checks. Unfortunately, those checks fail to take into
account integer promotion rules and are thus themselves subject to an integer
overflow. Cast the sizeof() operator to a uint64_t to force promotion while
multiplying.

Bug: 20139950

(cherry picked from commit e2e812e58e8d2716b00d7d82db99b08d3afb4b32)

Change-Id: I080eb3fa147601f18cedab86e0360406c3963d7b

uint32_t SampleTable::CompositionDeltaLookup::getCompositionTimeOffset(
 uint32_t sampleIndex) {
 Mutex::Autolock autolock(mLock);

 if (mDeltaEntries == NULL) {
 return 0;
 }

 if (sampleIndex < mCurrentEntrySampleIndex) {
        mCurrentDeltaEntry = 0;
        mCurrentEntrySampleIndex = 0;
 }

 while (mCurrentDeltaEntry < mNumDeltaEntries) {
 uint32_t sampleCount = mDeltaEntries[2 * mCurrentDeltaEntry];
 if (sampleIndex < mCurrentEntrySampleIndex + sampleCount) {
 return mDeltaEntries[2 * mCurrentDeltaEntry + 1];
 }

        mCurrentEntrySampleIndex += sampleCount;
 ++mCurrentDeltaEntry;
 }

 return 0;
}

uint32_t SampleTable::CompositionDeltaLookup::getCompositionTimeOffset(
 uint32_t sampleIndex) {
 Mutex::Autolock autolock(mLock);

 if (mDeltaEntries == NULL) {
 return 0;
 }

 if (sampleIndex < mCurrentEntrySampleIndex) {
        mCurrentDeltaEntry = 0;
        mCurrentEntrySampleIndex = 0;
 }

 while (mCurrentDeltaEntry < mNumDeltaEntries) {
 uint32_t sampleCount = mDeltaEntries[2 * mCurrentDeltaEntry];
 if (sampleIndex < mCurrentEntrySampleIndex + sampleCount) {
 return mDeltaEntries[2 * mCurrentDeltaEntry + 1];
 }

        mCurrentEntrySampleIndex += sampleCount;
 ++mCurrentDeltaEntry;
 }

 return 0;
}
