Auth: Rewrite mk_passwd in C

This patch drops the mk_passwd python script from auth plugin, by adding an equivalent C implementation.

The C implementation makes use of Monkey functions, whenever possible, so it links with Monkey objects.
In order to make the linking possible, some minor modifications had to be made to the configure script, monkey.c and mk_config.c source files.

Signed-off-by: Vladimir Cernov <gg.kaspersky@gmail.com>