alsa-lib: fix build with BR2_CONFIG_CACHE

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

CHANGES

@@ -20,9 +20,9 @@
 	New packages: divine, gvfs, libarchive, libmicrohttpd,
 	sdl_sound, swfdec, sysstat
 
-	Updated/fixed packages: alsamixergui, autoconf, bootutils, busybox,
-	gcc, directfb, dnsmasq, e2fsprogs, festival, gamin, gperf, gqview,
-	gstreamer, gst-plugins-bad, gst-plugins-base, gst-plugins-good,
+	Updated/fixed packages: alsa-lib, alsamixergui, autoconf, bootutils,
+	busybox, gcc, directfb, dnsmasq, e2fsprogs, festival, gamin, gperf,
+	gqview, gstreamer, gst-plugins-bad, gst-plugins-base, gst-plugins-good,
 	imagemagick, ipkg, iptables, iw, kernel-headers, kismet, leafpad,
 	libelf, libevent, libglib2, libidn, liblockfile, libmad, libpcap,
 	libupnp, libuuid, lighttpd, ltrace, lua, lzma, magiccube4d, matchbox,

package/multimedia/alsa-lib/alsa-lib.mk

@@ -39,6 +39,8 @@ endif
 
 ALSA_LIB_CONF_ENV = CFLAGS="$(ALSA_LIB_CFLAGS)" \
 		    LDFLAGS="$(TARGET_LDFLAGS) -lm"
+# the above doesn't work with shared config.cache
+ALSA_LIB_USE_CONFIG_CACHE = NO
 
 $(eval $(call AUTOTARGETS,package/multimedia,alsa-lib))