[processing] show wait cursor while updating alg list

Author: volaya

python/plugins/processing/core/Processing.py

@@ -155,8 +155,10 @@ def updateAlgsList():
         requires the list of algorithms to be created again from
         algorithm providers.
         """
+        QApplication.setOverrideCursor(QCursor(Qt.WaitCursor))
         Processing.loadFromProviders()
         Processing.fireAlgsListHasChanged()
+        QApplication.restoreOverrideCursor()
 
     @staticmethod
     def loadFromProviders():