Fixed ModuleInfo generation to no longer use the ModuleInfo class' default initializer for types/defaults, it's unsafe as initializers don't necesarily match the "formal" type. There might be explicit padding. Changed -g switch to emit DW_LANG_D debug info, make demangling work with a patched GDB, still more work to do for full support of D's Dwarf extensions. Added getNullValue helper method.

module typeinfo5;

void main()
{
    enum E : uint {
        A,B,C
    }
    auto ti = typeid(E);
    assert(ti.next() is typeid(uint));
    assert(ti.init is null);
}