fate: fix ENCMUX macro

This matches how it is actually being called.
Signed-off-by: Mans Rullgard <mans@mansr.com>

tests/Makefile

@@ -34,7 +34,7 @@ ENCDEC2 = $(call ALLYES, $(firstword $(1))_ENCODER $(lastword $(1))_DECODER  \
                          $(firstword $(3))_MUXER   $(lastword $(3))_DEMUXER)
 
 DEMDEC  = $(call ALLYES, $(1)_DEMUXER $(2:%=%_DECODER))
-ENCMUX  = $(call ALLYES, $(2:%=%_ENCODER) $(1)_MUXER)
+ENCMUX  = $(call ALLYES, $(1:%=%_ENCODER) $(2)_MUXER)
 
 include $(SRC_PATH)/tests/fate/acodec.mak
 include $(SRC_PATH)/tests/fate/vcodec.mak