FATE/opus: increase fuzz for the celt tests

This seems to be needed on some 32bit arches.

tests/fate/opus.mak

@@ -30,7 +30,7 @@ $(FATE_OPUS): CMP_UNIT = f32
 $(FATE_OPUS): FUZZ = 3
 
 $(FATE_OPUS_CELT): CMP = oneoff
-$(FATE_OPUS_CELT): FUZZ = 5
+$(FATE_OPUS_CELT): FUZZ = 6
 
 FATE_SAMPLES_AVCONV-$(call DEMDEC, MATROSKA, OPUS) += $(FATE_OPUS)
 fate-opus-celt: $(FATE_OPUS_CELT)