Change InputMessage.motion.pointerSize to a uint32_t.

This ensures it's the same size in both 32 and 64 bit
processes and also brings it in line with struct
MotionEntry.

(cherry-picked from bc6001b026069714177526eb1120b0011d6f2a51)

Change-Id: I28e87050478920a54132efbbb8138076ebad1409
Merge "Change InputMessage.motion.pointerSize to a uint32_t."
auto-merger: merge in from aosp/master