pgsql: Fix compilation with older OpenSSL versions

Fix compilation with older OpenSSL versions

Some older OpenSSL versions (0.9.8 branch) define TLS*_VERSION macros
but not the corresponding SSL_OP_NO_* macro, which causes the code for
handling ssl_min_protocol_version/ssl_max_protocol_version to fail to
compile. To fix, add more #ifdefs and error handling.

Reported-by: Victor Wagner <vitus(at)wagner(dot)pp(dot)ru>
Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Discussion: https://www.postgresql.org/message-id/flat/20190924101859.09383b4f%40fafnir.local.vm

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/4e6f101e921c9a7ff4e7fff847966b9cdd390753

Modified Files
--------------
src/backend/libpq/be-secure-openssl.c | 48 +++++++++++++++++++++++++++++++++--
1 file changed, 46 insertions(+), 2 deletions(-)