fix build (declare extern HashTable pdo_driver_hash)

Author: tony2001

ext/pdo/pdo.c

@@ -42,7 +42,7 @@ ZEND_DECLARE_MODULE_GLOBALS(pdo)
 /* True global resources - no need for thread safety here */
 
 /* the registry of PDO drivers */
-static HashTable pdo_driver_hash;
+HashTable pdo_driver_hash;
 
 /* we use persistent resources for the driver connection stuff */
 static int le_ppdo;

ext/pdo/php_pdo_int.h

@@ -22,6 +22,8 @@
 
 /* Stuff private to the PDO extension and not for consumption by PDO drivers
  * */
+
+extern HashTable pdo_driver_hash;
 extern zend_class_entry *pdo_exception_ce;
 int php_pdo_list_entry(void);