To force each backend implementation to really attempt to provide proper
random. If a proper random function is missing, then we can explicitly
make use of the default one we use when TLS support is missing.
This commit makes sure it works for darwinssl, gnutls, nss and openssl.
Before GnuTLS 3.3.6, the gnutls_x509_crt_check_hostname() function
didn't actually check IP addresses in SubjectAltName, even though it was
explicitly documented as doing so. So do it ourselves...
The AES-GCM ciphers were added to GnuTLS as late as ver. 3.0.1 but
the code path in which they're referenced here is only ever used for
somewhat older GnuTLS versions. This caused undeclared identifier errors
when compiling against those.
This seems to have become necessary for SRP support to work starting
with GnuTLS ver. 2.99.0. Since support for SRP was added to GnuTLS
before the function that takes this priority string, there should be no
issue with backward compatibility.
Make GnuTLS old and new consistent, specify the desired protocol, cipher
and certificate type in always in both modes. Disable insecure ciphers
as reported by howsmyssl.com. Honor not only --sslv3, but also the
--tlsv1[.N] switches.
Related Bug: http://curl.haxx.se/bug/view.cgi?id=1323
