BUG/MINOR: ssl: Missing return value check in ssl_ocsp_response_print

BUG/MINOR: ssl: Missing return value check in ssl_ocsp_response_print

When calling ssl_ocsp_response_print which is used to display an OCSP
response's details when calling the "show ssl ocsp-response" on the CLI,
we use the BIO_read function that copies an OpenSSL BIO into a trash.
The return value was not checked though, which could lead to some
crashes since BIO_read can return a negative value in case of error.

This patch should be backported to 2.5.