Use u32->VkImageCopy instead of u64.
Use u32->VkImageCopy instead of u64.

RegionCount is 32-bit anyway, so we cannot ever get a 64-bit value.
Fixes 1199.

baldwinn860/gapid,pmuetschard/gapid,baldwinn860/gapid,Qining/gapid,dsrbecky/gapid,Qining/gapid,pmuetschard/gapid,Qining/gapid,dsrbecky/gapid,google/agi,google/gapid,baldwinn860/gapid,pmuetschard/gapid,google/gapid,Qining/gapid,dsrbecky/gapid,google/agi,Qining/gapid,Qining/gapid,baldwinn860/gapid,google/agi,dsrbecky/gapid,google/agi,baldwinn860/gapid,dsrbecky/gapid,pmuetschard/gapid,dsrbecky/gapid,Qining/gapid,Qining/gapid,dsrbecky/gapid,pmuetschard/gapid,google/gapid,pmuetschard/gapid,google/gapid,google/gapid,google/agi,dsrbecky/gapid,google/agi,pmuetschard/gapid,google/agi,google/gapid,google/gapid,pmuetschard/gapid,google/agi,baldwinn860/gapid,baldwinn860/gapid,baldwinn860/gapid,google/gapid