configure.ac: don't install the static libraries

One should always be using the shared libraries.

Spotted while going through the Debian packaing.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>