package/numactl: fix musl build

Fixes:

  http://autobuild.buildroot.net/results/355/3555cd0abe68b6f0e2b2089af5ce26dbc4c73df6/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
[Thomas: rename patch and improve its description.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>