Remove pointless -vn option, the file has no video stream.

Originally committed as revision 25314 to svn://svn.ffmpeg.org/ffmpeg/trunk

tests/fate2.mak

@@ -125,7 +125,7 @@ fate-atrac3-3: CMP = oneoff
 fate-atrac3-3: REF = $(SAMPLES)/atrac3/mc_sich_at3_132_small.pcm
 
 FATE_TESTS += fate-gsm
-fate-gsm: CMD = framecrc -t 10 -i $(SAMPLES)/gsm/sample-gsm-8000.mov -vn
+fate-gsm: CMD = framecrc -t 10 -i $(SAMPLES)/gsm/sample-gsm-8000.mov
 
 FATE_TESTS += fate-gsm-ms
 fate-gsm-ms: CMD = framecrc -i $(SAMPLES)/gsm/ciao.wav