Fix crash on ARM in sceKernelMemcpy().

Happened with unaligned addresses only.  Fixes #1889.

I think I must've made a mistake while testing (maybe I forgot to change a .java file one run or needed a make clean on the ndk?), but now this consistently fixes it.  I'm guessing *(u64 *) on an address that isn't aligned to 4 is not okay on ARM.

I tried to maintain the overlap behavior.

-[Unknown]