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 bug77;
import tango.stdc.string;
void main()
{
    size_t len;
    void func2()
    {
        char* prefix = "";

        void func()
        {
        len = strlen(prefix);
        assert(len == 0);
        }

        func();
    }
    func2();
}