Log Message:
Update maildrop to 3.1.6

Deliver makedat and makedatprog directly in ${PREFIX}/bin to avoid conflicts \ 
with courier-imap.

Changes since 3.0.0:
* maildrop: fix compilation error.
* Fix spurious gcc 13 compiler warnings.
* Updated Dovecode authentication fix.
* Fix build with Dovecot authentication turned on.
* Update to C++11, replacing internal classes with modern C++ library classes.
* Fix the -V command line option to also explicitly set VERBOSE, fix assorted -V \ 
logging bugs.
* all: update configure.ac to require at least version 2.0.5 of libidn
* maildrop: remove unsafe SIGALRM handler.