Merge branch 'dm/port'

Add a few more knobs for new platform ports can tweak.

* dm/port:
  git-compat-util.h: do not #include <sys/param.h> by default
  Generalize the inclusion of strings.h
  Detect when the passwd struct is missing pw_gecos
  Support builds when sys/param.h is missing

diff --cc Makefile
Simple merge

diff --cc configure.ac
Simple merge