news/nzbget: Switch default option from GNUTLS to OPENSSL

There are a series of reports of TLS handshake failures from users of the port.
Upstream responds to this reports with "Use OpenSSL instead of GNU TLS".
Therefore the maintainer decided to switch the default option to OPENSSL.

PR: 215788
Submitted by: Toxic (maintainer)
MFH: 2017Q1