fdo#39007: blind fix for renamed OS X restore-state file

Remove also a potential restorecount.txt file (as reported in the bug) in addition to a potential restorecount.plist.

Change-Id: I96fb688e9dda804f240cad8f2109c5880b544302
Reviewed-on: https://gerrit.libreoffice.org/7239
Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>