Fix possible missing definition for syslog

Thank you Anatol Belski for noticing.

Author: Patrick Allaert

Zend/zend_errors.c

@@ -22,6 +22,7 @@
 #include "zend_errors.h"
 #include "php.h"
 #include "php_globals.h"
+#include "php_syslog.h"
 #include "SAPI.h"
 #include "ext/standard/html.h"