separate the 3 functions midirecord uses from libaudio.a into its own
file and link it directly, instead of having an (implicit) dependancy
on usr.bin/audio/common being built before usr.bin/midirecord is linked.

branches: 1.1.2;
add a program to record midi files from /dev/music.

this doesn't process several potential result that netbsd does
not output on /dev/music, and should be largely complete for
our current sequencer(4).