build/gen_stub.php: fix superfluous new line on enum case generation

Author: m6w6

build/gen_stub.php

@@ -1608,7 +1608,7 @@ public function __construct(string $name, ?Expr $value) {
     public function getDeclaration(): string {
         $escapedName = addslashes($this->name);
         if ($this->value === null) {
-            $code = "\n\tzend_enum_add_case_cstr(class_entry, \"$escapedName\", NULL);\n";
+            $code = "\tzend_enum_add_case_cstr(class_entry, \"$escapedName\", NULL);\n";
         } else {
             $evaluator = new ConstExprEvaluator(function (Expr $expr) {
                 throw new Exception("Enum case $this->name has an unsupported value");