ext/pdo: Move default fetch flags into bitfield

We don't need to reserve 32 bits when they fit in 9

Author: Girgias

ext/pdo/php_pdo_driver.h

@@ -577,7 +577,10 @@ struct _pdo_stmt_t {
 	 * bindParam() for its prepared statements, if false, PDO should
 	 * emulate prepare and bind on its behalf */
 	uint16_t supports_placeholders:2;
-	uint16_t reserved: 12;
+
+	/* defaults for fetches */
+	uint16_t default_fetch_type:9;
+	uint16_t reserved:3;
 
 	/* keep track of bound input parameters.  Some drivers support
 	 * input/output parameters, but you can't rely on that working */
@@ -595,9 +598,6 @@ struct _pdo_stmt_t {
 	 * */
 	int32_t column_count;
 
-	/* defaults for fetches */
-	enum pdo_fetch_type default_fetch_type;
-
 	union {
 		int column;
 		struct {