Remove 4 broken macros from ocsp.h

There were 4 macros in ocsp.h that have not worked since 1.1.0 because
they attempt to access the internals of an opaque structure.

For OCSP_REQUEST_sign() applications should use OCSP_request_sign() instead.
For OCSP_BASICRESP_sign() applications should use OCSP_basic_sign() instead.
For OCSP_REQUEST_verify() applications should use OCSP_request_verify()
instead.
For OCSP_BASICRESP_verify() applications should use OCSP_basic_verify()
instead.

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4635)