bug 4711: SubjectAlternativeNames is missing in some generated certificates

bug 4711: SubjectAlternativeNames is missing in some generated certificates

Squid may generate certificates which have a Common Name, but do not have
a subjectAltName extension. For example when squid generated certificates
do not mimic an origin certificate or when the certificate adaptation
algorithm sslproxy_cert_adapt/setCommonName is used.

This is causes problems to some browsers, which validates a certificate using
the SubjectAlternativeNames but ignore the CommonName field.

This patch fixes squid to always add a SubjectAlternativeNames extension in
generated certificates which do not mimic an origin certificate.

Squid still will not add a subjectAltName extension when mimicking an origin
server certificate, even if that origin server certificate does not include
the subjectAltName extension. Such origin server may have problems when
talking directly to browsers, and patched Squid is not trying to fix those
problems.

This is a Measurement Factory project