smaller improvements; jmc@ and nicm@ both ask me to get this in because
further tweaking will be easier in-tree

is NULL, and third-party software is starting to rely upon this.
Adapted from FreeBSD via Jona Joachim (jaj ; hcl-club , .lu), with minor
tweaks from nicm@ and yours truly.

jasper@

a section will help people looking for just the MALLOC_OPTIONS.
ok otto@ jmc@

use-after-free bugs; ok krw@ dlg@ pirofti@

individual pages (based on the existing string man pages). By Tim van
der Molen (tbvdm at xs4all dot nl) after a suggestion by millert@.
ok deraadt

the wcsdup example.
ok stsp

ok deraadt matthew

rather than returning so that realname still gets assigned.
ok millert@ deraadt@ thib@

no security, for consistency.  use of this option is discouraged. :)
ok deraadt guenther millert

cases.

position zero, skipping a random number of free slots and then
picking the next free one. This slowed things down, especially if
the number of full slots increases.
This changes the scannning to start at a random position in the
bitmap and then taking the first available free slot, wrapping if
the end of the bitmap is reached. Of course we'll still scan more
if the bitmap becomes more full, but the extra iterations skipping
free slots and then some full slots are avoided.
The random number is derived from a global, which is incremented
by a few random bits every time a chunk is needed (with a small optimization
if only one free slot is left).
Thanks to the testers!

1UL to 1U.

thanks to all testers.

tree, no idea where it came from; ok millert@ jmc@

to return -1 in case of an unprintable character.
ok nicm jmc

ok guenther

argv and don't suppress the handling of leading '-' in optstring when
POSIXLY_CORRECT is set.
Based on patch from Eric Blake.
ok and manpage update from millert@, manpage ok jmc@

invokes handlers registered with __cxa_atexit().
"seems right" deraadt@

the \: roff escape is an optional line break.

ok jmc@ jsing@

OK jsing@

ok deraadt@ djm@

path and realpath are the same.  This matches the manual and avoids
a bogus cast to non-const.  OK jsing@, previous version OK kettenis@

tested for a while by me.
ok otto@

Tweaks from jmc@
ok jmc@ krw@

ok krw@

ok krw@