Don't print the entire declaration of the alliassee when `->toChars()` is called on an `AliasDeclaration`; just printing the name will do. This fixes #305, which otherwise tries to generate {{{ class E { void A() { alias /* recurse into E->toCBuffer() */ m; } } }}} by way of an infinite recursion (causing a segfault when the stack runs out).

struct Vector {
        union { float x; float y; }
        const static Vector zero = { x : 0, y : 0 };
}

struct HBoxLayout {
        Vector padding  = Vector.zero;
}