Add delays in some timing funcs that games tightloop

Greatly improves performance in Legend of Heroes 1, which calls `sceKernelGetSystemTime()` and `sceKernelSysClock2USec()` over and over again.  Intro went from ~7 fps to ~60, but in game is only ~25 fps now (and still spending 5% time in these funcs.)  Dunno what it was before because I didn't have the patience to find out.

I'm not sure this timing is right, but it's hard to get accurate, and it can't be that far off I think.

May help other games that spin these funcs.

-[Unknown]