Fix alignment when getting slice in GrVkGpu for upload

Previous code would not align to 4 but not necessarily bytes-per-block.

Cq-Include-Trybots: luci.skia.skia.primary:Test-Debian10-Clang-NUC5PPYH-GPU-IntelHD405-x86_64-Debug-All-Vulkan
Change-Id: I06ffc9c38f52c645bafd22d0ac30712efb815e76
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345134
Auto-Submit: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

src/gpu/GrStagingBufferManager.cpp

@@ -19,7 +19,7 @@ GrStagingBufferManager::Slice GrStagingBufferManager::allocateStagingBufferSlice
     for (size_t i = 0; i < fBuffers.size(); ++i) {
         size_t totalBufferSize = fBuffers[i].fBuffer->size();
         size_t currentOffset = fBuffers[i].fOffset;
-        offset = GrAlignTo(currentOffset, requiredAlignment);
+        offset = ((currentOffset + requiredAlignment - 1)/requiredAlignment)*requiredAlignment;
         if (totalBufferSize - offset >= size) {
             buffer = &fBuffers[i];
             break;

src/gpu/vk/GrVkGpu.cpp

@@ -753,7 +753,12 @@ static size_t fill_in_regions(GrStagingBufferManager* stagingBufferManager,
 
     // Get a staging buffer slice to hold our mip data.
     // Vulkan requires offsets in the buffer to be aligned to multiple of the texel size and 4
-    size_t alignment = SkAlign4(bytesPerBlock);
+    size_t alignment = bytesPerBlock;
+    switch (alignment & 0b11) {
+        case 0:                     break;   // alignment is already a multiple of 4.
+        case 2:     alignment *= 2; break;   // alignment is a multiple of 2 but not 4.
+        default:    alignment *= 4; break;   // alignment is not a multiple of 2.
+    }
     *slice = stagingBufferManager->allocateStagingBufferSlice(combinedBufferSize, alignment);
     if (!slice->fBuffer) {
         return 0;