Remove library development files and all of libdmmp

Installing library development files seems problematic when it's unclear to me
if the ABI is stable, or if upstream cares at all about the ABI. Historically
there are no users of the multipath libraries outside of multipath(d) itself.
Recently qemu gained support for multipath reservations; when qemu wants to use
this, the multipath-tools maintainers need to understand the ABI status.

Disable building libdmmp completely, as no users seem to exist at all.

Gbp-Dch: full