Fix issue with streaming MOH failing if nobody is listening.

When a music class is setup to actually provide music on hold
from a stream we need to constantly read audio from it since it
will constantly be providing audio. This is now done despite there
being no channels listening to it.

(closes issue #14416)
Reported by: caspy


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@181655 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_musiconhold.c

@@ -557,11 +557,11 @@ static void *monmp3thread(void *data)
 			}
 			res = 8 * MOH_MS_INTERVAL;	/* 8 samples per millisecond */
 		}
-		if (AST_LIST_EMPTY(&class->members))
+		if (strncasecmp(class->dir, "http://", 7) && AST_LIST_EMPTY(&class->members))
 			continue;
 		/* Read mp3 audio */
 		len = ast_codec_get_len(class->format, res);
-		
+
 		if ((res2 = read(class->srcfd, sbuf, len)) != len) {
 			if (!res2) {
 				close(class->srcfd);