buildroot

mpd-mpc: bump to version 0.29

Since version 0.29 MPDs mpc only supports the meson build. Therefore,
adapt the package infrastructure according to the user manual.

Also add a hash for the license file.

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>