The function foreign-type-alignment returns the
alignment of type in bytes.
CFFI> (foreign-type-alignment :char) ⇒ 1 CFFI> (foreign-type-alignment :short) ⇒ 2 CFFI> (foreign-type-alignment :int) ⇒ 4
(defcstruct foo (a :char)) CFFI> (foreign-type-alignment '(:struct foo)) ⇒ 1