www/mod_wsgi: fix Python library linking

Always pass Python's LIBDIR to the linker instead of assuming that Apache's
LIBDIR is also a default linker search path.

Link mod_wsgi only against the shared libpython library. Do not append
Python's LIBS and SYSLIBS, which are intended for linking Python itself
or for static embedding. With NLS-enabled Python, those flags promote
libintl to a direct dependency of mod_wsgi and cause an unnecessary
gettext-runtime dependency.

This results in the intended dependency chain:

mod_wsgi.so -> libpython${PYTHON_VERSION}.so.1.0 -> libintl.so.8

rather than making libintl a direct dependency of mod_wsgi.

PR: 298985
Approved by: portmgr (blanket)
MFH: 2026Q4