pgsql: Replace px_memset() with explicit_bzero()

Replace px_memset() with explicit_bzero()

The former was trying to do the same as the latter, but the latter has
more robust and portable implementations, and it's the standard across
the tree, so replace and remove px_memset().

Co-authored-by: Dagfinn Ilmari Mannsåker <ilmari(at)ilmari(dot)org>
Discussion: https://www.postgresql.org/message-id/flat/a035c67f-4aa8-42e0-bb24-7b5abe927af4%40eisentraut.org
Discussion: https://www.postgresql.org/message-id/flat/87ldew2yqu.fsf%40wibble.ilmari.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/8534b0b4c765b06de30d249c9bacecc2d10ac68b

Modified Files
--------------
contrib/pgcrypto/crypt-blowfish.c | 4 ++--
contrib/pgcrypto/crypt-md5.c | 4 ++--
contrib/pgcrypto/crypt-sha.c | 4 ++--
contrib/pgcrypto/mbuf.c | 12 ++++++------
contrib/pgcrypto/pgp-cfb.c | 2 +-
contrib/pgcrypto/pgp-compress.c | 4 ++--
contrib/pgcrypto/pgp-decrypt.c | 20 ++++++++++----------
contrib/pgcrypto/pgp-encrypt.c | 10 +++++-----
contrib/pgcrypto/pgp-mpi.c | 2 +-
contrib/pgcrypto/pgp-pgsql.c | 2 +-
contrib/pgcrypto/pgp-pubenc.c | 6 +++---
contrib/pgcrypto/pgp-pubkey.c | 8 ++++----
contrib/pgcrypto/pgp-s2k.c | 6 +++---
contrib/pgcrypto/pgp.c | 2 +-
contrib/pgcrypto/px-crypt.c | 2 +-
contrib/pgcrypto/px-hmac.c | 8 ++++----
contrib/pgcrypto/px.c | 9 +--------
contrib/pgcrypto/px.h | 2 --
18 files changed, 49 insertions(+), 58 deletions(-)