spawn: FreeBSD needs libgen
Makefile: FreeBSD needs -lcrypt
spawn: use a builtin OS define

Will convert incrementally.
zlib: FreeBSD needs unistd.h for getopt()
pklist: fix type error with Heimdal

Heimdal defines krb5_data.data as a void*, not char*
pklist: implement printing of config data for Heimdal

...even though Heimdal doesn't even have config tickets yet.
pklist: detect MIT config tickets on Heimdal
thirdparty/logwipe: disable utmp, lastlog on FreeBSD
Makefile: FreeBSD has dlsym() in libc
Makefile: avoid "unused" warnings

On FreeBSD:
|   CC    strnatcmp.o (thirdparty/strnatcmp.c)
| cc: --as-needed: linker input file unused because linking not done
Makefile: remove some ugliness

KRB_LDLIBS only contains two items; assign LDLIBS to them normally.
Makefile: only echo the first input
Makefile: fix krb5.h dependencies

I forgot what 'order-only' means.
Makefile, logwipe: add a misc/feature.h to contain all feature defines
krb5.h: remove dead code