message: Clamp miplevel size to avoid zero width or height
  I was seeing a zero height in certain circumstances
  for textures in scenerendering.
diff: @@ -182,8 +182,8 @@ namespace vks
  bufferCopyRegion.imageSubresource.mipLevel = i;
  bufferCopyRegion.imageSubresource.baseArrayLayer = 0;
  bufferCopyRegion.imageSubresource.layerCount = 1;
  - bufferCopyRegion.imageExtent.width = ktxTexture->baseWidth >> i;
  - bufferCopyRegion.imageExtent.height = ktxTexture->baseHeight >> i;
  + bufferCopyRegion.imageExtent.width = std::max(1u, ktxTexture->baseWidth >> i);
  + bufferCopyRegion.imageExtent.height = std::max(1u, ktxTexture->baseHeight >> i);
  bufferCopyRegion.imageExtent.depth = 1;
  bufferCopyRegion.bufferOffset = offset;
  