add mkostemp, mkostemps, mkstemps from FreeBSD.

branches: 1.11.2; 1.11.8;
- ansify, knf.
- no functional changes

branches: 1.10.4; 1.10.20;
The tools/compat versions of mkstemp() and mkdtemp() need to call the
internal function that's usually named "__gettemp". However in a cross
build, "__gettemp" is in a namespace reserved for the host system, so we
can't use that. Use "__nbcompat_gettemp" instead, following the example
of several other functions or macros in tools/compat. Previously, this
was handled by using the name "gettemp", but that conflicts with the
local gettemp() function in dist/nawk.

A little libc namespace housekeeping exercise:
* Make vfprintf_unlocked() an internal function, c.f. __svfscanf_unlocked().
* Add internal names for arc4random(), endnetpath(), fhstatvfs(),
fstatvfs(), mkstemp(), shquote(), statvfs(), taddr2uaddr(), uaddr2taddr(),
uuid_create_nil(), uuid_is_nil(), and wcwidth().
* Include namespace.h where supposed to.

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).

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22280, verified by myself.

Merge the nathanw_sa branch.

Allow mktemp to be built as a host tool.

branches: 1.4.10; 1.4.12;
back out the #ifdef _DIAGNOSTIC argument checks; too many people complained.
_DIAGASSERT() is still retained.

* use _DIAGASSERT() to check pointer arguments against NULL and file
descriptors against -1 (as appropriate).
* add actual checks which to detect stuff that would trigger_DIAGASSERT(),
and attempt to return a sane error condition.
* knf some code
* remove some `register' decls.

the first two items result in the addition of code similar to the
following in various functions:

_DIAGASSERT(path != NULL)
#ifdef _DIAGNOSTIC
if (path == NULL) {
errno = EFAULT;
return (-1);
}
#endif

Add a mktempdir(), like mkstemp(), but it creates a directory.

If AUDIT, do not compile certain functions.