fate-mpeg4: use TARGET_SAMPLES for resize tests

tests/fate/mpeg4.mak

@@ -1,7 +1,7 @@
 
 MPEG4_RESOLUTION_CHANGE = down-down down-up up-down up-up
 
-fate-mpeg4-resolution-change-%: CMD = framemd5 -flags +bitexact -idct simple -i $(SAMPLES)/mpeg4/resize_$(@:fate-mpeg4-resolution-change-%=%).h263
+fate-mpeg4-resolution-change-%: CMD = framemd5 -flags +bitexact -idct simple -i $(TARGET_SAMPLES)/mpeg4/resize_$(@:fate-mpeg4-resolution-change-%=%).h263
 
 FATE_MPEG4-$(call DEMDEC, H263, H263) := $(addprefix fate-mpeg4-resolution-change-, $(MPEG4_RESOLUTION_CHANGE))