Reset llBit on thread switch.

Never actually seen ll used, though... but this way it should
work as advertized, as long as a syscall doesn't happen in between...

Core/HLE/sceKernelThread.cpp

@@ -1034,6 +1034,9 @@ void __KernelLoadContext(ThreadContext *ctx)
 	currentMIPS->fcr0 = ctx->fcr0;
 	currentMIPS->fcr31 = ctx->fcr31;
 	currentMIPS->fpcond = ctx->fpcond;
+
+	// Reset the llBit, the other thread may have touched memory.
+	currentMIPS->llBit = 0;
 }
 
 u32 __KernelResumeThreadFromWait(SceUID threadID)

Core/MIPS/MIPSInt.cpp

@@ -372,7 +372,7 @@ namespace MIPSInt
 				if (rt != 0) {
 					R(rt) = 1;
 				}
-			} else {
+			} else if (rt != 0) {
 				R(rt) = 0;
 			}
 			break;