CMake: please install man pages

[0-wiz-0]

When building with autoconf, the following man pages are installed that are not installed when building with CMake:

/usr/pkg/man/man1/mmdblookup.1
/usr/pkg/man/man3/MMDB_aget_value.3
/usr/pkg/man/man3/MMDB_close.3
/usr/pkg/man/man3/MMDB_dump_entry_data_list.3
/usr/pkg/man/man3/MMDB_free_entry_data_list.3
/usr/pkg/man/man3/MMDB_get_entry_data_list.3
/usr/pkg/man/man3/MMDB_get_metadata_as_entry_data_list.3
/usr/pkg/man/man3/MMDB_get_value.3
/usr/pkg/man/man3/MMDB_lib_version.3
/usr/pkg/man/man3/MMDB_lookup_sockaddr.3
/usr/pkg/man/man3/MMDB_lookup_string.3
/usr/pkg/man/man3/MMDB_open.3
/usr/pkg/man/man3/MMDB_read_node.3
/usr/pkg/man/man3/MMDB_strerror.3
/usr/pkg/man/man3/MMDB_vget_value.3
/usr/pkg/man/man3/libmaxminddb.3

Please install them also when using CMake. Thanks!