build: as ${gtk_version} is not used anymore, hardcode "3"
build: as ${gtk_version} is not used anymore, hardcode "3"

This branch does not have gtk# version distinction anymore,
so we add a hardcoded version "3" to the configure summary.

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