Include suffix on literal tokens

[dtolnay]

It looks like the integer literals emitted by const_random are plain integers without a type suffix. The below program compiles and prints i32, which is probably not what would be expected.

use const_random::const_random;

fn f<T>(_: T) {
    println!("{}", std::any::type_name::<T>());
}

fn main() {
    f(const_random!(u8));
}

The const_random invocation in this code should expand to 0xNNu8 instead.