Add explict conversion from int64_t to int
Add explict conversion from int64_t to int

The values after right shifts should fit into 32bit int. The commit
fixes MSVC build warning when new-quant is enabled.

Change-Id: Ic89dd86fb981a1206653943658af2b6b2925a676

GrokImageCompression/aom,GrokImageCompression/aom,mbebenita/aom,GrokImageCompression/aom,mbebenita/aom,luctrudeau/aom,mbebenita/aom,smarter/aom,GrokImageCompression/aom,GrokImageCompression/aom,smarter/aom,mbebenita/aom,smarter/aom,smarter/aom,smarter/aom,luctrudeau/aom,luctrudeau/aom,mbebenita/aom,mbebenita/aom,smarter/aom,luctrudeau/aom,luctrudeau/aom,mbebenita/aom,mbebenita/aom,GrokImageCompression/aom,luctrudeau/aom,mbebenita/aom