Discuss __KernelChangeThreadState

Related #6557
JPCSP emulator has this log but PPSSPP doesn't
94779 [user_main] INFO  hle.ThreadManForUser - DispatchThread disabled, not context switching to CsdThread(uid=0x55, Status=PSP_THREAD_READY, Priority=0x11, Wait=None, doCallbacks=false)

this commit base on  http://code.google.com/p/jpcsp/source/browse/trunk/src/jpcsp/HLE/modules150/ThreadManForUser.java#628
This commit do not fix the game