Add some header includes and detail reasons why

Author: Girgias

Zend/zend_language_scanner.h

@@ -20,7 +20,14 @@
 #ifndef ZEND_SCANNER_H
 #define ZEND_SCANNER_H
 
-#include "zend_globals.h"
+#include "zend_arena.h"
+#include "zend_ast.h"
+#include "zend_stack.h"
+#include "zend_ptr_stack.h"
+#include "zend_stream.h" /* For zend_file_handle */
+#include "zend_string.h"
+#include "zend_multibyte.h" /* For zend_encoding_filter and zend_encoding */
+#include "zend_globals.h" /* For zend_php_scanner_event */
 
 typedef struct _zend_lex_state {
 	unsigned int yy_leng;