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 bug21;
extern(C) int printf(char*, ...);

void main()
{
    int i = 42;
    auto a = {
        int j = i*2;
        auto b = {
            return j;
        };
        return b();
    };
    int i2 = a();
    printf("%d\n", i2);
    assert(i2 == i*2);
}