pgsql: Remove configure check for OpenSSL's SSL_get_current_compression

Remove configure check for OpenSSL's SSL_get_current_compression()

This function has been added in OpenSSL 0.9.8, which is the oldest
version supported on HEAD, so checking for it at configure time is
useless.  Both the frontend and backend code did not even bother to use
it.

Reported-by: Daniel Gustafsson
Author: Michael Paquier
Reviewed-by: Daniel Gustafsson, Tom Lane
Discussion: https://postgr.es/m/20191205083252.GE5064@paquier.xyz
Discussion: https://postgr.es/m/98F7F99E-1129-41D8-B86B-FE3B1E286881@yesql.se

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/28f4bba66b572d6b3b8dc4fcf4e585821e0a5363

Modified Files
--------------
configure                     | 2 +-
configure.in                  | 2 +-
src/include/pg_config.h.in    | 3 ---
src/include/pg_config.h.win32 | 3 ---
src/include/port.h            | 4 ----
5 files changed, 2 insertions(+), 12 deletions(-)