Problem:
$ make /bin/bash ../libtool --mode=install /usr/bin/install -c libupnp.la '/usr/local/lib' libtool: error: error: cannot install 'libupnp.la' to a directory not ending in /usr/lib
Solution:
$ make clean
Solution source: https://groups.google.com/forum/#!topic/protobuf/3CxS0Gb7tM8