alsa-utils: disable on no-mmu platforms (fork)

alsa-utils uses fork which is not available on targets without MMU support.
It seems to be possible to replace fork with vfork in alsa-utils, but we do
not like to carry such patches in buildroot without them being accepted
upstream.

Fixes
http://autobuild.buildroot.org/results/9f8/9f8e572c9f1c677155cc7d1828371bcf572ff878

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/alsa-utils/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_ALSA_UTILS
 	bool "alsa-utils"
+	depends on BR2_USE_MMU # fork
 	depends on BR2_LARGEFILE
 	depends on BR2_TOOLCHAIN_HAS_THREADS # alsa-lib
 	select BR2_PACKAGE_ALSA_LIB
@@ -10,6 +11,7 @@ config BR2_PACKAGE_ALSA_UTILS
 	  http://www.alsa-project.org/
 
 comment "alsa-utils needs a toolchain w/ largefile, threads"
+	depends on BR2_USE_MMU # fork
 	depends on !BR2_LARGEFILE || !BR2_TOOLCHAIN_HAS_THREADS
 
 if BR2_PACKAGE_ALSA_UTILS