FATE: add a pattern rule for generating asynth wav files

tests/Makefile

@@ -19,7 +19,10 @@ tests/data/asynth1.sw: tests/audiogen$(HOSTEXESUF) | tests/data
 tests/data/asynth-16000-1.sw: tests/audiogen$(HOSTEXESUF) | tests/data
 	$(M)./$< $@ 16000 1
 
-tests/data/asynth%.sw tests/vsynth%/00.pgm: TAG = GEN
+tests/data/asynth-%.wav: tests/audiogen$(HOSTEXESUF) | tests/data
+	$(M)./$< $@ $(subst -, ,$*)
+
+tests/data/asynth% tests/vsynth%/00.pgm: TAG = GEN
 
 include $(SRC_PATH)/tests/fate/aac.mak
 include $(SRC_PATH)/tests/fate/ac3.mak