Configure: remove superfluous 0x

The number is taken from the OPENSSL_VERSION_NUMBER which is already
in the hex form.

CLA: trivial

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1706)

(cherry picked from commit 35a498e4)