Update type inference for ZEND_STRLEN

Since PHP 8.0, this cannot return NULL anymore, the only possible return
value is long. See https://wiki.php.net/rfc/consistent_type_errors.

Author: nielsdos

Zend/Optimizer/zend_inference.c

@@ -3569,12 +3569,6 @@ static zend_always_inline zend_result _zend_update_type_info(
 			UPDATE_SSA_TYPE(MAY_BE_RC1|MAY_BE_RCN|MAY_BE_ANY|MAY_BE_ARRAY_KEY_ANY|MAY_BE_ARRAY_OF_ANY, ssa_op->result_def);
 			break;
 		case ZEND_STRLEN:
-			tmp = MAY_BE_LONG;
-			if (t1 & (MAY_BE_ANY - (MAY_BE_NULL|MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_LONG|MAY_BE_DOUBLE|MAY_BE_STRING))) {
-				tmp |= MAY_BE_NULL;
-			}
-			UPDATE_SSA_TYPE(tmp, ssa_op->result_def);
-			break;
 		case ZEND_COUNT:
 		case ZEND_FUNC_NUM_ARGS:
 			UPDATE_SSA_TYPE(MAY_BE_LONG, ssa_op->result_def);