Detect EOF while reading in libssl

Detect EOF while reading in libssl

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: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/10907)