Macro auto_bitflags_h

macro_rules! auto_bitflags_h {
    (u16, $shift_num:expr, $flag_name:ident) => { ... };
    (u32, $shift_num:expr, $flag_name:ident) => { ... };
    (u64, $shift_num:expr, $flag_name:ident) => { ... };
}

Helper macro for auto_bitflags, don’t call this directly.