alsa-utils: needs dynamic library support

Since recent bumps of alsa-lib and alsa-utils, alsa-lib installs
<alsa/topology.h>, which alsa-utils uses to build an alsatplg program
which requires <dlfcn.h>. Therefore, alsa-utils now needs dynamic
library support.

Fixes:

  http://autobuild.buildroot.net/results/7ba954e03822d758e25356935b0dfc2c91d3712a/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>