pgsql: Add gen_random_uuid function

Add gen_random_uuid function

This adds a built-in function to generate UUIDs.

PostgreSQL hasn't had a built-in function to generate a UUID yet,
relying on external modules such as uuid-ossp and pgcrypto to provide
one. Now that we have a strong random number generator built-in, we
can easily provide a version 4 (random) UUID generation function.

This patch takes the existing function gen_random_uuid() from pgcrypto
and makes it a built-in function. The pgcrypto implementation now
internally redirects to the built-in one.

Reviewed-by: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
Discussion: https://www.postgresql.org/message-id/6a65610c-46fc-2323-6b78-e8086340a325@2ndquadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5925e5549890416bcf588334d9d0bc99f8ad6c7f

Modified Files
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contrib/pgcrypto/pgcrypto.c | 16 ++--------------
doc/src/sgml/datatype.sgml | 12 ++----------
doc/src/sgml/func.sgml | 26 ++++++++++++++++++++++++++
doc/src/sgml/pgcrypto.sgml | 3 ++-
doc/src/sgml/uuid-ossp.sgml | 11 +++--------
src/backend/utils/adt/uuid.c | 20 ++++++++++++++++++++
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.dat | 3 +++
src/test/regress/expected/opr_sanity.out | 1 +
src/test/regress/expected/uuid.out | 10 ++++++++++
src/test/regress/sql/uuid.sql | 6 ++++++
11 files changed, 76 insertions(+), 34 deletions(-)