Zend/Optimizer/block_pass.c: remove useless variable declaration and assignment

src is already VAR_SOURCE(opline->op2) from before the if condition

Author: Girgias

Zend/Optimizer/block_pass.c

@@ -822,7 +822,6 @@ static void zend_optimize_block(zend_basic_block *block, zend_op_array *op_array
 					    src->extended_value == IS_STRING &&
 					    src->op1_type != IS_CONST) {
 						/* convert T1 = CAST(STRING, X), T2 = CONCAT(Y, T1) to T2 = CONCAT(Y,X) */
-						zend_op *src = VAR_SOURCE(opline->op2);
 						VAR_SOURCE(opline->op2) = NULL;
 						COPY_NODE(opline->op2, src->op1);
 						MAKE_NOP(src);