libshairplay: needs avahi with libdnssd compat option at runtime

libshairplay uses dlopen to open libdnssd at runtime (unless dlopen() isn't
available, then static linking is used - But avahi depends on
!BR2_PREFER_STATIC_LIB so that isn't possible), so ensure avahi is available.

Fixes http://autobuild.buildroot.net/results/54d/54de48b23439cef4cbea3b8a65b20e2a8b049f67/

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libshairplay/Config.in

@@ -2,11 +2,17 @@ config BR2_PACKAGE_LIBSHAIRPLAY
 	bool "libshairplay"
 	depends on BR2_INET_IPV6
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	depends on BR2_USE_MMU # avahi
+	depends on !BR2_PREFER_STATIC_LIB # avahi
+	select BR2_PACKAGE_AVAHI
+	select BR2_PACKAGE_AVAHI_DAEMON
+	select BR2_PACKAGE_AVAHI_LIBDNSSD_COMPATIBILITY # runtime
 	help
 	  libshairplay is a client library that emulates an airplay
 	  server.
 
 	  https://github.com/juhovh/shairplay
 
-comment "libshairplay needs a toolchain w/ IPv6, threads"
-	depends on !BR2_INET_IPV6 || !BR2_TOOLCHAIN_HAS_THREADS
+comment "libshairplay needs a toolchain w/ IPv6, threads, dynamic library"
+	depends on BR2_USE_MMU
+	depends on !BR2_INET_IPV6 || !BR2_TOOLCHAIN_HAS_THREADS || BR2_PREFER_STATIC_LIB