avformat/hls: don't propagate deprecated "user-agent" AVOption

This code will print a warning if any user agent is set - even if the
API user used the proper non-deprecated "user_agent" option.

This change should not even break anything, because even if the user
sets the deprecated "user-agent" option, http.c copies it to the
"user_agent" option anyway.

libavformat/hls.c

@@ -1593,7 +1593,7 @@ static int save_avio_options(AVFormatContext *s)
 {
     HLSContext *c = s->priv_data;
     static const char * const opts[] = {
-        "headers", "http_proxy", "user_agent", "user-agent", "cookies", "referer", "rw_timeout", NULL };
+        "headers", "http_proxy", "user_agent", "cookies", "referer", "rw_timeout", NULL };
     const char * const * opt = opts;
     uint8_t *buf;
     int ret = 0;