Bug#917467: wmbiff: tlscomm_expect() does not handle EAGAIN or GNUTLS_E_AGAIN (TLS 1.3)

[Nye Liu]

Package: wmbiff

With TLS 1.3, gnutls will return GNUTLS_E_AGAIN even if the underlying 
transport socket is a blocking socket.

https://gitlab.com/gnutls/gnutls/issues/644#note_123363338