autogen.sh: Honor NOCONFIGURE=1

See http://people.gnome.org/~walters/docs/build-api.txt

Hdg: I know this may seem unnecessary since we also have bootstrap.sh, but
the Gnome people are doing continues build testing of Gnome + dependencies
and having all autogen.sh scripts support NOCONFIGURE=1 makes live easier for
them. Note that in return we get "free" continues build-testing and patches
and / or a heads up when we break things.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Prepare for 1.0.16-rc1 release

Signed-off-by: Hans de Goede <hdegoede@redhat.com>