libc: Sync qsort(3) with FreeBSD revision r318515.

r279663: enhance to handle 32-bit aligned data on 64-bit systems

r279666: qsort(3): small style(9) cleanups.

r288030: Use ANSI C prototypes.  Eliminates -Wold-style-definition
warnings.

r318514: Use size_t.

r318515: Reduce the possible recursion level to log2(N) by always
recursing on the smaller partition instead.

Bug: 38450217
Test: builds, ./tests/run-on-host.sh 64
Change-Id: Ieb622e6f54f8f6d6f62e1bdb491d3b5c8e2f9965