widget/termwindow.cpp: use frameBuffer->Clear() only in verbose mode

frameBuffer->Clear() is not required if yaft window was not visible.
Otherwise frameBuffer->Clear() will clean screen at possible background operations e.g. updatechecks, thats not so good if we have opened
messages, menues, screensaver or other gui stuff.
Hope this has no bad side effects with scripts, plugins or what ever.


Origin commit data
------------------
Commit: 786f82e076
Author: Thilo Graf <dbt@novatux.de>
Date: 2020-01-13 (Mon, 13 Jan 2020)

src/gui/widget/termwindow.cpp

@@ -121,8 +121,8 @@ void CTermWindow::showResult()
 
 			} while (msg != CRCInput::RC_ok && msg != CRCInput::RC_home && msg != CRCInput::RC_timeout);
 		}
+		frameBuffer->Clear();
 	}
-	frameBuffer->Clear();
 }
 
 #if 0