od: initialize type-size tables statically

od: initialize type-size tables statically

* src/od.c (NO_SIZE): Make it explicitly 0, as the
initializers now rely on this.
(MAX_INTEGRAL_TYPE_SIZE): Remove.  All uses replaced by
ARRAY_CARDINALITY (integral_type_size) - 1.
Move static assertion down to where this can be used.
(integral_type_size, fp_type_size): Make them const,
and initialize them statically.
(main): Omit no-longer-needed initialization code.