mk: generate internal library dependencies

mk: generate internal library dependencies

Up to now dependencies between DPDK internal libraries have been
untracked at shared library level, requiring applications to know
about library internal dependencies and often consequently overlinking.

Since the dependencies are already recorded for build ordering in the
makefiles with DEPDIRS-y we can use that information to generate LDLIBS
entries for internal libraries automatically.

Also revert commit 8180554d82b3 ("vhost: fix linkage of driver with
library") which is made redundant by this change.

Signed-off-by: Panu Matilainen <pmatilai@redhat.com>
Acked-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>