refactor(bin): replace define with const in tpc.php

- Changed TYPEPHP_PHP_SCRIPT_ENTRY from define to const declaration
- Maintained same boolean value of true for the constant
- Updated syntax to use PHP const keyword instead of define function

bin/tpc.php

@@ -5,5 +5,5 @@ require __DIR__ . '/../src/polyfills.php';
 require __DIR__ . '/../src/gen_stub.php';
 require __DIR__ . '/../src/compiler.php';
 
-define('TYPEPHP_PHP_SCRIPT_ENTRY', true);
+const TYPEPHP_PHP_SCRIPT_ENTRY = true;
 main($argc, $argv);