package/alsa-utils: re-enable in BR2_STATIC_LIBS configuration

In commit 4707383c ("alsa-utils: needs
dynamic library support"), we added a !BR2_STATIC_LIBS dependency
because topology/topology.c was including <dlfcn.h>.

However, it turns out that this include is not needed/used at all, so
we can instead drop it, and re-enable the package in BR2_STATIC_LIBS
configuration.

This was discovered when analyzing why we have
package/alsa-lib/0003-alsa-lib-conditionally-enable-libdl-in-AM_PATH_ALSA-.patch. This
patch fixes the AM_PATH_ALSA autoconf macro, used by alsa-utils, so
that ALSA_LIBS doesn't carry the -ldl option, fixing static-linking
scenarios. This patch had become useless since alsa-utils was no
longer available in BR2_STATIC_LIBS configuration.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>