In shell scripts invoked during a build, and in crunchgen, use ${AWK}
instead of plain "awk". The Makefiles that invoke these scripts
or programs will pass AWK=${HOST_AWK:Q}.

Homogenize usage messages: make the 'usage' word all lowercase, as this seems
to be the most common practice in our tree.

Import pdksh V5.2.14.
Includes lots of bugfixes.