Treat the file as invalid if we have no valid formats for it (issue #7643 reported by KNK)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@38825 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_musiconhold.c

@@ -219,7 +219,7 @@ static int ast_moh_files_next(struct ast_channel *chan)
 			state->pos %= state->class->total_files;
 
 			/* check to see if this file's format can be opened */
-			if (ast_fileexists(state->class->filearray[state->pos], NULL, NULL) != -1)
+			if (ast_fileexists(state->class->filearray[state->pos], NULL, NULL) > 0)
 				break;
 
 		}