Use 'z' as the format specifier for size_t

Using 'lu' will produce a compiler warning for some versions of gcc and on some
architectures. 'z' should be portable as a format specifier for size_t.
........

Merged revisions 400812 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@400813 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_pjsip_header_funcs.c

@@ -294,7 +294,7 @@ static int read_header(void *obj)
 	plen = strlen(p);
 	if (plen + 1 > data->len) {
 		ast_log(AST_LOG_ERROR,
-				"Buffer isn't big enough to hold header value.  %lu > %lu\n", plen + 1,
+				"Buffer isn't big enough to hold header value.  %zu > %zu\n", plen + 1,
 				data->len);
 		return -1;
 	}