Add support for finding the version of SSL/TLS in use.

Previously we allowed you to specify which version(s) you wanted to use,
but did not provide access to the version that was actually negotiated.

[ChangeLog][QtNetwork][QSslSocket] Add support for finding the version
of SSL/TLS in use by a connection.

Task-number: QTBUG-28471
Change-Id: I6d50d2bc9f1ce7f98192e67992178fe7e41c0575
Reviewed-by: Peter Hartmann <phartmann@blackberry.com>
Add accessors for the build-time version of openssl.

Many bugs originate due to mismatches between the build-time and
run-time versions of openssl but they're hard to debug as we don't
provide access to the build-time info. This addresses that weakness.

[ChangeLog][QtNetwork][QSslSocket] Added accessors for the version
of openssl used at build-time. This will help when debugging
problems caused by a mismatch with the run-time version.

Change-Id: I6a4c21c8f16ab4c90cdf166f38c62fe37bf1f165
Reviewed-by: Peter Hartmann <phartmann@blackberry.com>