Use "-nostdinc -iwithprefix include" to prevent the inclusion of
system header files, but still permitting *compiler* header files.

Break off execute() into its own source file, with the intent of being
able to re-use it for a CLI module.

H. Peter Anvin wrote:
> Erwan: I would have to get you to do this, since it would mean
> changing the license (trying to keep libcom32 under the BSD/MIT
> licenses), and you have them under your own copyright (as opposed to
> mine), which means I can't do this change.

Please find attached the patch to changing the license to MIT on modules
I did contribute in com32/modules/.

Rename plaintext documentation from doc/*.doc to doc/*.txt, to avoid
the chronic problem of web sites thinking they're in MS-Word format.
Sigh.  As if Microsoft somehow had a monopoly on the word "document".

When printing error messages about configuration files, don't
necessarily call it "syslinux.cfg".