sysutils/pfstat: Fix build on FreeBSD 15, take maintainership

pf.c:174:16: error: use of undeclared identifier 'DIOCGETSTATUS'

174 |         if (ioctl(fd, DIOCGETSTATUS, &s)) {
    |                       ^

Improve port:

• Replace PORTVERSION with DISTVERSION.
• Remove legacy unnecessary MAKE_ARGS and REINPLACE_CMD.
• Replace REINPLACE_CMD in pf.c with CFLAGS+=-I/usr/include/net.
• Reduce number of INSTALL_* calls in do-install.

PR: 291607
MFH: 2025Q4
Co-authored-by: David Marec <david.marec@proton.me>
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>
(cherry picked from commit c701d6805046f1928a33188d265821b4579204c3)