Have a shared library version thats reasonable with our version scheme

The FAQ says this:

    After the release of OpenSSL 1.0.0 the versioning scheme changed. Letter
    releases (e.g. 1.0.1a) can only contain bug and security fixes and no
    new features. Minor releases change the last number (e.g. 1.0.2) and
    can contain new features that retain binary compatibility. Changes to
    the middle number are considered major releases and neither source nor
    binary compatibility is guaranteed.

With such a scheme (and with the thinking that it's nice if the shared
library version stays on track with the OpenSSL version), it's rather
futile to keep the minor release number in the shared library version.
The deed already done with OpenSSL 1.0.x can't be changed, but with
1.x.y, x=1 and on, 1.x as shared library version is sufficient.

Reviewed-by: Kurt Roeckx <kurt@openssl.org>