* src/main.c
Prevent bug #981 (sc 2.3.1 segfaults with
gtk+ 2.10) from being reported again:
if Sylpheed-Claws has been compiled against
GTK+ < 2.9.0 and we're running with GTK+ >= 2.9.0,
of if Sylpheed-Claws has been compiled against
GTK+ >= 2.9.0 and we're running with GTK+ < 2.9.0,
error out.