qtvcp: another attempt to prevent segfaults on exit

Author: snowgoer540

src/emc/usr_intf/qtvcp/qtvcp.py

@@ -507,4 +507,4 @@ def excepthook(self, exc_type, exc_obj, exc_tb):
         from qtvcp.core import Status, Info, Qhal, Path
 
         _qtvcp = QTVCP()
-        sys.exit(_app)
+        os._exit(_app)