Function rb_sys::rb_thread_call_without_gvl

pub unsafe extern "C" fn rb_thread_call_without_gvl(
    func: Option<unsafe extern "C" fn(arg1: *mut c_void) -> *mut c_void>, 
    data1: *mut c_void, 
    ubf: rb_unblock_function_t, 
    data2: *mut c_void
) -> *mut c_void