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).

module union4;

union U {
    struct { float x,y,z; }
    float[3] xyz;
}

void main() {
    const float[3] a = [1f,2,3];
    U u = U(1,2,3);
    assert(u.xyz == a);
    assert(u.x == 1);
    assert(u.y == 2);
    assert(u.z == 3);
}