fate: convert psx-str to a demuxer test

While these codecs are covered elsewhere, the container is different
from the other psx-str file.
Signed-off-by: Mans Rullgard <mans@mansr.com>

tests/fate/demux.mak

@@ -40,8 +40,8 @@ fate-nsv-demux: CMD = framecrc -i $(SAMPLES)/nsv/witchblade-51kbps.nsv -t 6 -vco
 FATE_AVCONV += fate-oma-demux
 fate-oma-demux: CMD = crc -i $(SAMPLES)/oma/01-Untitled-partial.oma -acodec copy
 
-FATE_AVCONV += fate-psx-str
-fate-psx-str: CMD = framecrc -i $(SAMPLES)/psx-str/descent-partial.str
+FATE_AVCONV += fate-psx-str-demux
+fate-psx-str-demux: CMD = framecrc -i $(SAMPLES)/psx-str/descent-partial.str -c copy
 
 FATE_AVCONV += fate-psx-str-v3-mdec
 fate-psx-str-v3-mdec: CMD = framecrc -i $(SAMPLES)/psx-str/abc000_cut.str -an