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 scope2;
extern(C) int printf(char*, ...);
void main()
{
    scope(exit) printf("exit\n");
    scope(failure) printf("failure\n");
    scope(success) printf("success\n");
}