avutil/avstring: Factor av_match_list() out

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/avstring.c

@@ -402,6 +402,27 @@ end:
     return ret;
 }
 
+int av_match_list(const char *name, const char *list, char separator)
+{
+    const char *p;
+    char ext1[128], *q;
+    int i;
+
+    p = list;
+    for (i = 1;; i++) {
+        q = ext1;
+        while (*p != '\0' && *p != separator  && q - ext1 < sizeof(ext1) - 1)
+            *q++ = *p++;
+        *q = '\0';
+        if (!av_strcasecmp(ext1, name))
+            return i;
+        if (*p == '\0')
+            break;
+        p++;
+    }
+    return 0;
+}
+
 #ifdef TEST
 
 int main(void)