first component is now a package name+version/pattern, no more
executable/patchname/whatnot.
While there, introduce BUILD_USES_MSGFMT as shorthand to pull in
devel/gettext unless /usr/bin/msgfmt exists (i.e. on post-1.5 -current).
Patch by Alistair Crooks <agc@netbsd.org>
using the newest PNG library won't work on system with an older one. To
prevent such problems with precompiled binary packages require at least
"png-1.0.9nb1" in all dependences.
