Suppress a compiler warning due to discarding a "const" qualifier

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@90928 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_voicemail.c

@@ -4283,7 +4283,7 @@ static int forward_message(struct ast_channel *chan, char *context, struct vm_st
 
 			/* play name if available, else play extension number */
 			snprintf(fn, sizeof(fn), "%s%s/%s/greet", VM_SPOOL_DIR, receiver->context, s);
- 			RETRIEVE(fn, -1, s, receiver->context);
+ 			RETRIEVE(fn, -1, (char *)s, receiver->context);
 			if (ast_fileexists(fn, NULL, NULL) > 0) {
 				res = ast_stream_and_wait(chan, fn, ecodes);
 				if (res) {