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

main/stdtime/localtime.c

@@ -2304,6 +2304,7 @@ int ast_strftime_locale(char *buf, size_t len, const char *tmp, const struct ast
 	long fraction;
 	const char *prevlocale;
 
+	buf[0] = '\0';/* Ensure the buffer is initialized. */
 	if (!format) {
 		return -1;
 	}