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).

void main()
{
    int[4] a = [1,2,3,4];
    int[4] b = [5,6,7,8];
    a[] += b[] / 2;
    assert(a[0] == 3);
    assert(a[1] == 5);
    assert(a[2] == 6);
    assert(a[3] == 8);
}