Fix some uninitialized buffers for CDR handling valgrind found.

* Made ast_strftime_locale() ensure that the output buffer is initialized.
The std library strftime() returns 0 and does not touch the buffer if it
has an error.  However, the function can also return 0 without an error.

(closes issue ASTERISK-22412)
Reported by: rmudgett
........

Merged revisions 397902 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@397903 65c4cc65-6c06-0410-ace0-fbb531ad65f3

funcs/func_cdr.c

@@ -213,6 +213,8 @@ static int cdr_read(struct ast_channel *chan, const char *cmd, char *parse,
 		AST_APP_ARG(options);
 	);
 
+	buf[0] = '\0';/* Ensure the buffer is initialized. */
+
 	if (!chan) {
 		return -1;
 	}