clang compiler warnings: Fix sometimes-uninitialized warning in pbx_config

This patch fixes a warning caught by clang, in which a char pointer could be
assigned to before it was initialized. The patch re-organizes the code to
ensure that the pointer is always initialized, even on off nominal paths.

Review: https://reviewboard.asterisk.org/r/4529

ASTERISK-24917
Reported by: dkdegroot
patches:
  rb4529.patch submitted by dkdegroot (License 6600)
........

Merged revisions 434090 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 434091 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@434092 65c4cc65-6c06-0410-ace0-fbb531ad65f3

pbx/pbx_config.c

@@ -956,7 +956,9 @@ static char *handle_cli_dialplan_save(struct ast_cli_entry *e, int cmd, struct a
 					const char *el = ast_get_extension_label(p);
 					char label[128] = "";
 					char *appdata = ast_get_extension_app_data(p);
-					char *escaped;
+
+					int escaped_len = (!ast_strlen_zero(appdata)) ? 2 * strlen(appdata) + 1 : 1;
+					char escaped[escaped_len];
 
 					if (ast_get_extension_matchcid(p)) {
 						sep = "/";
@@ -970,12 +972,9 @@ static char *handle_cli_dialplan_save(struct ast_cli_entry *e, int cmd, struct a
 					}
 
 					if (!ast_strlen_zero(appdata)) {
-						int escaped_len = 2 * strlen(appdata) + 1;
-						char escaped[escaped_len];
-
 						ast_escape_semicolons(appdata, escaped, escaped_len);
 					} else {
-						escaped = "";
+						escaped[0] = '\0';
 					}
 
 					fprintf(output, "exten => %s%s%s,%d%s,%s(%s)\n",