Return uint32 from Log2FloorNonZero64
Return uint32 from Log2FloorNonZero64

A uint32 is big enough to hold any return value from that function, and
doing it this way prevents compiler warnings in coded_stream.h about
narrowing a uint64 to a uint32.

google/protobuf,google/protobuf,google/protobuf,Livefyre/protobuf,Livefyre/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,Livefyre/protobuf,google/protobuf,google/protobuf,google/protobuf,Livefyre/protobuf,Livefyre/protobuf