Log Message:
Make this compile on Linux and IRIX and increase odds of working on
other non-NetBSD platforms as well (though they may need ALL_TARGET
tweaking):
- apparently some versions of Linux/gcc combinations require
  the header file errno.h included in each file in order for
  it to link (otherwise, it will compile (!?) but bail out
  when linking)
- set ALL_TARGET to LOWER_OPSYS
  this works for netbsd and linux, and should work for the other bsds
  at least.
- set ALL_TARGET differently for IRIX
- use CFLAGS instead of hard-coded ABI flags for IRIX 6
- some install-sh/install can not handle multiple files/directories at
  once.  Newer bootstrapped versions can, but for systems that still
  have the older one we may as well split this for better compatibility.