qmmp-plugin-pack: Drop off RPATH hack

This patch no longer needed since
-DCMAKE_INSTALL_RPATH_USE_LINK_PATH:BOOL=TRUE
is defined in PORTSDIR/Mk/Uses/cmake.mk macro.

Thanks for Max Brazhnikov,
http://www.freebsd.org/cgi/query-pr.cgi?pr=185219
qmmp, qmmp-plugin-pack: Update .include <macro>

Use the latest pair of bsd.port.options.mk and bsd.port.mk
instead of bsd.port.pre.mk and bsd.port.post.mk