I think if you use CPPFLAGS (and probably LDFLAGS) to point to the
headers and the library location, the right things should happen.
Right, and I checked `./configure --help':
Some influential environment variables:
CPPFLAGS (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if
you have headers in a nonstandard directory <include dir>
`MACHINES' doesn't have OpenBSD hints. It does have `FreeBSD', but that
doesn't mention the need to have the iconv package and use CPPFLAGS.