Still the Debian Sid based Crunchbang ?
Today's Debian Sid has libglib2.0-0 version 2.32.2,
and it uses libffi5 : libffi.so.5
If you have the libffi.so.6 from libffi 3.0.11 in a hideaway location,
glib 2.32.1 may not be able to find it.
Anyway, gimp-2.8.0 will do fine with glib-2.30.2, which is often
compiled to use libffi.so.4 or libffi.so.5