The author of the code has released an update for GPSMan. The
appended patch brings the astro/gpsman port up-to-date so that
it builds GPSMan-6.2.1.
I also took the opportunity to fix the order of some of the
entries om pkg-plist so they were in numeric order (because
of an oversight on my part when I built the 6.2 port).
This appears to just be a bugfix release.
Fix: Apply the following patch, then