main/libmaxminddb: split -libs to don't force cronjob installation
Without this commit, the cronjob is unconditionally installed. Even for software which only uses libmaxminddb as a library. On my system, wireshark pulls in libmaxminddb and libmaxminddb cronjob outputs:
No MaxMind license key found; exiting. Please enter your license key into /etc/libmaxminddb.cron.conf.
weekly even though I don't use MaxMind directly on my system. By splitting the -libs subpackage we can ensure that package which depend on libmaxminddb don't pull in the cronjob by default.
CC: @fabled