tests/audiomatch: Fix compile warning

Making sure bestpos is initialized to zero to prevent gcc from kvetching.
It's harmless (although it's not obvious that it's harmless)
from code inspection:
tests/audiomatch.c: In function ‘main’:
tests/audiomatch.c:40: warning: ‘bestpos’ may be used uninitialized in this function

Thanks to Moritz Barsnick for first bringing this to the attention.
Signed-off-by: LiuQi <liuqi@gosun.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

tests/audiomatch.c

@@ -37,7 +37,7 @@ int main(int argc, char **argv){
     FILE *f[2];
     int i, pos;
     int siglen, datlen;
-    int bestpos;
+    int bestpos = 0;
     double bestc=0;
     double sigamp= 0;
     int16_t *signal, *data;