madplay: fix alsa detection/linking using host-pkgconf

Fixes [1]: configure check for libasound failed because of missing
pthread linkage.

[1] http://autobuild.buildroot.net/results/f3a/f3a0b3ff15e729d223c8c8ee6af75c425cd344b6/

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/madplay/madplay.mk

@@ -15,7 +15,8 @@ MADPLAY_DEPENDENCIES = libmad libid3tag $(if $(BR2_PACKAGE_GETTEXT),gettext)
 # ./configure can find alsa-lib.
 ifeq ($(BR2_PACKAGE_MADPLAY_ALSA),y)
 MADPLAY_CONF_OPTS += --with-alsa
-MADPLAY_DEPENDENCIES += alsa-lib
+MADPLAY_DEPENDENCIES += host-pkgconf alsa-lib
+MADPLAY_CONF_ENV += LIBS="$(shell $(PKG_CONFIG_HOST_BINARY) --libs alsa)"
 endif
 
 $(eval $(autotools-package))