#31 Add pam_listfile like functionality

[Carter]

I was managing user access through pam with a
pam_listfile (i.e. file with usernames) and then if the
user was found in the file, pam_smbpass for
authenticating against an NT domain.

However, I wanted to set up a simple database instead
of a text file, thus my patch was born.

I would have patched the newest pam_mysql, but 0.6.0
was the newest in gentoo/portage at the time..
Hopefully this patch easily fits into the newer
version, if not, I can provide a newer patch.

[Carter]

pam_mysql.c-0.6.0.patch to add nopasswdcheck option