Remove the cast from the definition of OPENSSL_VERSION_NUMBER

If a cast is included in the definition it cannot be used in preprocessor
expressions, e.g. "#if OPENSSL_VERSION_NUMBER > 0x10000000L"

[extended tests]

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7839)