Enhance/fix VMS exit code handling.

* commands.c, function.c, hash.c, job.c, main.c, output.c:
use MAKE exit codes.
* makeint.h: encode make exit codes so that they are VMS compatible.
* job.c: check child exit code for VMS style exit codes.
* vmsjobs.c: save and return VMS style exit code.
8 files changed