Undeprecate OpenSSL_version_num and OPENSSL_VERSION_NUMBER

Undeprecate OpenSSL_version_num and OPENSSL_VERSION_NUMBER

The OpenSSL_version_num() function returns at runtime the
OPENSSL_VERSION_NUMBER of the compiled OpenSSL library.  This is a
used and useful interface, and should not (at least yet) be
deprecated, we just introduced the new versioning schema, it seems
too early to deprecate the old.

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7853)