Build the windll structure.

def make_windll(structs):
    """
    Build the windll structure.
    """
    name = 'windll_t'
    var = 'windll'
    struct_def = """
typedef struct _{0} {{
{1}
}}
{0};
""".strip().format(name, ''.join(structs))
    x86 = reloc_var(var, 'reloc_delta', True, name)
    x64 = '{0} *{1} = &_{1};\n'.format(name, var)
    return struct_def, x86, x64