configure: depend on tp-glib with Subject.
configure: depend on tp-glib with Subject.

Actually, a slightly earlier version of telepathy-glib, on the unstable
0.15.x branch, includes Subject, but we may as well depend on the stable
branch: it includes fixes for Empathy bugs.

Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets