add patch to fix a crash if n_messages is zero and causes a divide by zero

Add a patch which fixes a divide by zero floating point exception if n_messages is zero in onmi-area.

This exception is happening randomly while endeavour is idling in background.

Here is the upstream issue: https://gitlab.gnome.org/World/Endeavour/-/issues/496

added priority3-normal statusunconfirmed labels

assigned to @heftig

merged