In an action alleging violations of the Fair Housing Act (FHA), 42 U.S.C. section 3604(f)(3)(C), which, in turn, constituted housing discrimination against persons with disabilities, the District Court dismissed the complaint for failure to state a claim is affirmed where the design and accessibility requirements of the FHA do not apply to a commercial building that was originally constructed before the requirements' effective date, but converted into residential units after that date.