lang/maude: fix build on GCC architectures

Don't link unconditinally with $NCURSESLIB. When NCURSESLIB is /usr/lib and the system compiler is base GCC, GCC from ports (currently GCC9) is used. Passing -L/usr/lib makes GCC try to link to base libstdc++ instead the one from ports.

Also add USES=localbase:ldflags.

PR: 239481
Approved by: linimon (mentor), greg@unrelenting.technology (maintainer)
Differential Revision: https://reviews.freebsd.org/D21397