app_voicemail: Don't split mailbox options on comma

Because the per-mailbox options are the last thing on a line, don't look
for or stomp on any subsequent commas.

ASTERISK-27935 #close
Reported by: Sébastien Duthil

Change-Id: I07b2eb4a33c303d0c7114d5b906f8c067c60a153

apps/app_voicemail.c

@@ -12531,8 +12531,8 @@ static int append_mailbox(const char *context, const char *box, const char *data
 	if (stringp && (s = strsep(&stringp, ","))) {
 		ast_copy_string(vmu->pager, s, sizeof(vmu->pager));
 	}
-	if (stringp && (s = strsep(&stringp, ","))) {
-		apply_options(vmu, s);
+	if (stringp) {
+		apply_options(vmu, stringp);
 	}
 
 	switch (vmu->passwordlocation) {