pgsql: Make Port->ssl_in_use available, even when built with !USE_SSL

Make Port->ssl_in_use available, even when built with !USE_SSL

Code that check the flag no longer need #ifdef's, which is more convenient.
In particular, makes it easier to write extensions that depend on it.

In the passing, modify sslinfo's ssl_is_used function to check ssl_in_use
instead of the OpenSSL specific 'ssl' pointer. It doesn't make any
difference currently, as sslinfo is only compiled when built with OpenSSL,
but seems cleaner anyway.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/e453cc2741416dc784842b2bba68749556cf0f6f

Modified Files
--------------
contrib/sslinfo/sslinfo.c | 2 +-
src/backend/libpq/hba.c | 10 +---------
src/include/libpq/libpq-be.h | 10 ++++++----
3 files changed, 8 insertions(+), 14 deletions(-)