Reject invalid constructed encodings.

According to X6.90 null, object identifier, boolean, integer and enumerated
types can only have primitive encodings: return an error if any of
these are received with a constructed encoding.
Reviewed-by: Emilia Käsper <emilia@openssl.org>

(cherry picked from commit f5e4b6b5b566320a8d774f9475540f7d0e6a704d)