buildroot

alsa-utils: convert to autotargets and bump to 1.0.23

[ Thomas: remove all patches, since they have been merged. Implement
  the target uninstallation step, fix many issues. ]

[Peter: fix target install / uninstall steps]
Signed-off-by: Martin Banky <Martin.Banky@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>