Work around build a failure with Clang 11 on head.

/wrkdirs/usr/ports/java/openjdk11/work/openjdk-jdk11u-jdk-11.0.8-10-1/src/java.desktop/unix/native/libawt_xawt/xawt/XlibWrapper.c:2186:12:
error: cast to smaller integer type 'jint' (aka 'int') from 'int (*)(Display *)' (aka 'int (*)(struct _XDisplay *)')
[-Werror,-Wpointer-to-int-cast]

return (jint) XSynchronize((Display*)jlong_to_ptr(display), (onoff == JNI_TRUE ? True : False));
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

1 error generated.

It looks like a false-positive, though.