upmpdcli: fix static linking issue

Fixes:
http://autobuild.buildroot.net/results/7ed/7ed85071bc06b4806e90b278a0736ea70c01b456/



Upmpdcli forgets to take the dependencies of libupnpp into consideration,
breaking static linking, so help it.

Libupnpp unfortunately doesn't provide a .pc file, so manually handle its
dependencies here.

The build system doesn't expand LIBS from the configure step, so manually
pass it to make.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>