pgsql: Refactor SQL functions of SHA-2 in cryptohashfuncs.c

Refactor SQL functions of SHA-2 in cryptohashfuncs.c

The same code pattern was repeated four times when compiling a SHA-2
hash. This refactoring has the advantage to issue a compilation warning
if a new value is added to pg_cryptohash_type, so as anybody doing an
addition in this area would need to consider if support for a new SQL
function is needed or not.

Author: Sehrope Sarkuni, Michael Paquier
Discussion: https://postgr.es/m/YA7DvLRn2xnTgsMc@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f854c69a5b36ba7aa85bee9e9590c3e517970156

Modified Files
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src/backend/utils/adt/cryptohashfuncs.c | 138 +++++++++++++-------------------
1 file changed, 54 insertions(+), 84 deletions(-)