If we hit an EOF while reading in libssl then we will report an error
back to the application (SSL_ERROR_SYSCALL) but errno will be 0. We add
an error to the stack (which means we instead return SSL_ERROR_SSL) and
therefore give a hint as to what went wrong.

Contains a partial fix for #10880
Reviewed-by: NTomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: NDmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/10882)