Prevent crashes caused by nested event loops run when renaming inline

When renaming inline and starting a drag or invoking the context menu,
a nested event loop will be run. If the role editor loses focus and
emits roleEditingFinished(), we must prevent that deleteLater() is
called because this would delete the role editor inside a nested event
loop which is run from one of its own functions. We would get a crash
when returning from that event loop otherwise.

BUG: 308018
BUG: 309421
FIXED-IN: 4.9.4