include unistd.h where getmode is traditionally declared

branches: 1.7.6; 1.7.8; 1.7.10;
Remove clause 3 and 4 from TNF licenses

branches: 1.6.30;
White space nit.

Use the first argument of getmode() to modify the second arg, instead of
just replacing the second arg. This lets the higher order file type bits
survive. Fixes problems with the tools version of mknod(8).

KNF.

Overhaul how `build.sh tools' are used:

* Rename "config.h" to "nbtool_config.h" and
HAVE_CONFIG_H to HAVE_NBTOOL_CONFIG_H.
This makes in more obvious in the source when we're using
tools/compat/config.h versus "standard autoconf" config.h

* Consistently move the inclusion of nbtool_config.h to before
<sys/cdefs.h> so that the former can provide __RCSID() (et al),
and there's no need to protect those macros any more.

These changes should make it easier to "tool-ify" a program by adding:
#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
to the top of the source files (for the general case).

Include config.h unconditionally; clean up.

Make many host tools compile on non-NetBSD hosts. Not complete, but
very nearly there.