[0.4.9] cherry-pick [CRT] Reimplement qsort() using FreeBSD implementation.

[0.4.9] cherry-pick [CRT] Reimplement qsort() using FreeBSD implementation.

Our implementation had a bug that could be triggered while
building our USBD library on ReactOS: the compare function
could be called with a NULL pointer instead of a valid value.

With this bug fixed (and the cmd hack in CORE-14648), ReactOS
can totally selfhost :-)! I was able to build LiveCD and BootCD
without any trouble, crash, deadlock or whatever.
(Next step: having a buildbot slave hosted on ReactOS ;-)).

Enjoy: https://twitter.com/HeisSpiter/status/1002880397103988737

CORE-14680

(cherry picked from commit 2dfe5e3f463ca4d7eb920d25c2a33b29a70f3e27)