autogen.sh: prefer automake 1.11 if available, for silent rules
autogen.sh: prefer automake 1.11 if available, for silent rules

This mirrors a similar change in telepathy-glib.

Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,jku/telepathy-gabble,mlundblad/telepathy-gabble,jku/telepathy-gabble,Ziemin/telepathy-gabble,jku/telepathy-gabble,mlundblad/telepathy-gabble,mlundblad/telepathy-gabble