gnutls: fix an async handshake crash
gnutls: fix an async handshake crash

g_tls_connection_gnutls_handshake_async() would cause a crash if the
handshake either succeeded or failed immediately (rather than getting
an EAGAIN after making partial progress).

https://bugzilla.gnome.org/show_bug.cgi?id=658771

Distrotech/glib-networking,GNOME/glib-networking,GNOME/glib-networking,Distrotech/glib-networking,Distrotech/glib-networking,GNOME/glib-networking