VMS: bs-nl and command handling fixes.

[John E. Malmberg]

This patch is a complete rewrite of the VMS command parser.

In order to support the existing VMS recipe syntax which is a 
combination of VMS and Posix shell syntax, VMS had to reparse the action 
lines to simulate the Posix shell syntax.

The existing parsing code was making too many incorrect assumptions 
about how DCL and POSIX syntax are actually written and needed a 
complete rewrite.  It was also just estimating the size of the buffer to 
build the command and never doing any bounds checking.

This new code knows the VMS DCL limitations and better parses the action 
lines.  While a temporary command file may still be used in some cases, 
redirection no longer uses temporary files.

Before this fix: 43 out of 466 tests fail.
After this fix:  21 out of 466 tests fail.

Backwards compatibility note:  The old parser tolerated some DCL syntax 
errors that the new parser does not allow.

Regards,
-John

0001-Fix-bs-nl-handling-for-VMS.patch
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