pgsql: Make some use of anonymous unions [pgcrypto]

Make some use of anonymous unions [pgcrypto]

Make some use of anonymous unions, which are allowed as of C11, as
examples and encouragement for future code, and to test compilers.

This commit changes some structures in pgcrypto.

Reviewed-by: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/f00a9968-388e-4f8c-b5ef-5102e962d997%40eisentraut.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/efcd5199d8cb8e5098f79b38d0c46004e69d1a46

Modified Files
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contrib/pgcrypto/openssl.c | 14 +++++++-------
contrib/pgcrypto/px.h | 2 +-
src/common/cryptohash.c | 36 ++++++++++++++++++------------------
3 files changed, 26 insertions(+), 26 deletions(-)