JIT: set clear_cache_asap to false when clearing the cache

Would probably result in continual cache-clearing if the stack overflow code
in the BLR optimizations triggers.

Source/Core/Core/PowerPC/Jit64/Jit.cpp

@@ -223,6 +223,7 @@ void Jit64::ClearCache()
 	trampolines.ClearCodeSpace();
 	farcode.ClearCodeSpace();
 	ClearCodeSpace();
+	m_clear_cache_asap = false;
 }
 
 void Jit64::Shutdown()