build: Fix configure failure with --disable-gnome (bgo#698347)
build: Fix configure failure with --disable-gnome (bgo#698347)

BANSHEE_CHECK_GCONF sets the HAVE_DBUS_GLIB conditional, and is not
called if --disable-gnome is passed to configure. But conditionals must
always be set, so set it to false by default.

Signed-off-by: Bertrand Lorentz <eb7ac131ef7bff6d2ebccd6e5bf9a7cb6485cf2c@gmail.com>

GNOME/banshee,babycaseny/banshee,arfbtwn/banshee,stsundermann/banshee,dufoli/banshee,Carbenium/banshee,stsundermann/banshee,GNOME/banshee,babycaseny/banshee,GNOME/banshee,Carbenium/banshee,Carbenium/banshee,dufoli/banshee,Carbenium/banshee,arfbtwn/banshee,arfbtwn/banshee,Carbenium/banshee,ixfalia/banshee,stsundermann/banshee,ixfalia/banshee,stsundermann/banshee,dufoli/banshee,babycaseny/banshee,dufoli/banshee,babycaseny/banshee,arfbtwn/banshee,ixfalia/banshee,GNOME/banshee,ixfalia/banshee,ixfalia/banshee,ixfalia/banshee,dufoli/banshee,arfbtwn/banshee,arfbtwn/banshee,babycaseny/banshee,stsundermann/banshee,dufoli/banshee,GNOME/banshee,GNOME/banshee,babycaseny/banshee,ixfalia/banshee,stsundermann/banshee,GNOME/banshee,babycaseny/banshee,dufoli/banshee,GNOME/banshee,dufoli/banshee,babycaseny/banshee,Carbenium/banshee,arfbtwn/banshee,stsundermann/banshee,ixfalia/banshee,arfbtwn/banshee,stsundermann/banshee