pgsql: Change pgcrypto to use the new ResourceOwner mechanism.

Change pgcrypto to use the new ResourceOwner mechanism.

This is a nice example of how extensions can now use ResourceOwners to
track extension-specific resource kinds

Reviewed-by: Peter Eisentraut, Andres Freund
Discussion: https://www.postgresql.org/message-id/d746cead-a1ef-7efe-fb47-933311e876a3%40iki.fi

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/cd694f60dc975e9fe41e8643ca6f0629283d102e

Modified Files
--------------
contrib/pgcrypto/openssl.c | 181 +++++++++++++++++++--------------------------
1 file changed, 78 insertions(+), 103 deletions(-)