Fast path CallSyscall where possible.

It seems we're spending a decent amount of time there, which isn't
entirely unexpected.  We can eliminate some things easily.
Clear the jit cache when toggling debug stats.

This way we can bypass that check normally, for speed.
Oops, avoid a crash on a bad HLE func.

In the debug stats area.
Correct sceKernelIsCpuIntrSuspended().

It takes a param.  Verified by tests, it just returns what the param
means, not anything about the current state.