Introduce split packages postfix-{cdb,ldap,lmdb,mysql,pcre,pgsql,sqlite},
which allows for a slimmer installation, while not pulling in
all available database backends, if they are not required.
Add upstream PGP key 622C7C012254C186677469C50C0B590E80CA15A7 to
validpgpkeys (Wietse Venema <wietse@porcupine.org>).
Add HAS_LMDB to CFLAGS to actually build the lmdb feature.
Add split packages to postfix' optdepends.
Add .install file for postfix notifying the users about the change in
packaging.
Remove obsolete postfix-tools from conflicts/provides/replaces.
Remove unreproducible makedefs file also from postfix-files.
Introduce drop-in files for dynamicmaps.cf and postfix-files for
each of the split packages.