*/*njs: fix build on FreeBSD 15

/usr/local/include/quickjs/quickjs.h:996:34: error: cast from 'JSCFunctionMagic *' (aka 'struct JSValue (*)(struct JSContext *, struct JSValue, int, struct JSValue *, int)') to 'JSCFunction *' (aka 'struct JSValue (*)(struct JSContext *, struct JSValue, int, struct JSValue *)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]

996 |     return JS_NewCFunction2(ctx, (JSCFunction *)func, name, length, cproto, magic);
    |                                  ^~~~~~~~~~~~~~~~~~~

1 error generated.