Fix breakage of GIN support for varchar[] and cidr[] that I introduced in the

Fix breakage of GIN support for varchar[] and cidr[] that I introduced in the
operator-family rewrite.  I had mistakenly supposed that these could use the
pg_amproc entries for text[] and inet[] respectively.  However, binary
compatibility of the underlying types does not make two array types binary
compatible (since they must differ in the header field that gives the element
type OID), and so the index support code doesn't consider those entries
applicable.  Add back the missing pg_amproc entries, and add an opr_sanity
query to try to catch such mistakes in future.  Per report from Gregory
Maxwell.