alsa-lib: fix build on bfin

Bfin toolchains don't have versionsort (which alsa-lib needs), so fake it
using alphasort instead.

Fixes http://autobuild.buildroot.net/results/cf760651b2e238842813bf0882011b5fbb898c0d

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

package/alsa-lib/alsa-lib.mk

@@ -70,6 +70,12 @@ ifeq ($(BR2_SOFT_FLOAT),y)
 ALSA_LIB_CONF_OPT += --with-softfloat
 endif
 
+ifeq ($(BR2_bfin),y)
+# blackfin external toolchains don't have versionsort. Fake it using alphasort
+# instead
+ALSA_LIB_CFLAGS += -Dversionsort=alphasort
+endif
+
 ALSA_LIB_CONF_ENV = CFLAGS="$(ALSA_LIB_CFLAGS)" \
 		    LDFLAGS="$(TARGET_LDFLAGS) -lm"