I get this message:
nacho@gandalf:~/build-lenmus/build$ make -j2
Linking CXX executable bin/lenmus
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_subscribe_port'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_event_input'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_queue_tempo_set_ppq'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_queue_tempo_set_tempo'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_disconnect_to'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_set_capability'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_close'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_free_queue'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_set_port_specified'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_sizeof'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_disconnect_from'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_get_name'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_alloc_queue'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_query_next_port'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_event_output'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_set_port'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_subscribe_set_sender'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_delete_port'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_strerror'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_subscribe_sizeof'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_drain_output'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_create_port'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_event_input_pending'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_midi_event_new'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_query_next_client'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_get_capability'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_midi_event_free'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_get_client'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_queue_status_get_tick_time'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_client_info_get_client'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_client_id'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_connect_to'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_queue_tempo_sizeof'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_subscribe_set_time_real'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_get_port'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_control_queue'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_set_client'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_midi_event_encode_byte'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_client_info_sizeof'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_open'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_get_queue_status'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_info_set_type'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_client_info_set_client'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_queue_status_sizeof'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_subscribe_set_time_update'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_port_subscribe_set_dest'
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libportmidi.so: undefined reference to `snd_seq_set_queue_tempo'
collect2: ld devolvió el estado de salida 1
make[2]: *** [bin/lenmus] Error 1
make[1]: *** [CMakeFiles/lenmus.dir/all] Error 2
make: *** [all] Error 2