ansify - drop the K&R style prototypes & implementations.

Fix -Wcast-qual issues

branches: 1.9.40;
Revert previous changes. Add a comment to the source explaining the
reason things are as they are -- Perry said:
This (using err("mailwrapper")) is intentional. Mailwrapper plays ugly
games with argv[0] and thus it is often difficult for people to know
that the error isn't from "mailq" or "sendmail" but from
mailwrapper -- having mailwrapper add an indication that it was really
mailwrapper running was a requested feature.

Correct args to err(), no need to include "mailwrapper:" prefix manually.
Triggered by posting to OpenBSD mailing list.

Actually make additional arguments in mailer.conf useful, and document
them.
Reviewed by perry and wiz.

tweaks for fparseln(3) move from libutil to libc:
- remove #include <util.h> if nothing else needed it
- remove LDFLAGS+=-lutil if nothing else needed it

branches: 1.5.2;
convert to use getprogname()

Add forgottern addarg(&al, NULL, 0) before execve() to prevent coredump.

branches: 1.3.8;
Allow remapped commands to have arguments appended to them.

- Rewrite to use fparseln(), strspn(), strsep(). Avoids statically-sized
buffers and allows for line continuation.
- Use __progname instead of chopping argv[0] into a statically-sized
temporary buffer.

Add the "mailwrapper" program, which is designed to act as a switch
permitting users to choose between sendmail and other mail systems with a
simple configuration file change. Not yet turned on -- this is being
committed so people can beat on it.