Set file descriptors to -1 on creation, so that we don't see weirdness later.

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@305129 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_musiconhold.c

@@ -1159,6 +1159,8 @@ static struct mohclass *moh_class_malloc(void)
 
 	if ((class = ao2_alloc(sizeof(*class), moh_class_destructor))) {
 		class->format = AST_FORMAT_SLINEAR;
+		class->srcfd = -1;
+		class->pseudofd = -1;
 	}
 
 	return class;