pgsql: Use be_tls_* API for SSL information in sslinfo

Use be_tls_* API for SSL information in sslinfo

sslinfo was passing the Port->ssl member directly to OpenSSL in order
to extract information regarding the connection. This breaks the API
provided by the backend TLS implementation, as well as duplicates code
for no benefit. Rewrite to make use of the backend API as much as
possible.

Author: Daniel Gustafsson <daniel@yesql.se>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5d1833f414973595411779b86e085fb05907a805

Modified Files
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contrib/sslinfo/sslinfo.c | 139 ++++++++++++++++------------------------------
doc/src/sgml/sslinfo.sgml |   4 +-
2 files changed, 49 insertions(+), 94 deletions(-)