[PATCH] Detail SSL handshake failures

This patch allows Squid to provide details for the %D macro on the
secure connect failed error page when an SSL handshake with the origin
server fails.
The default %D text is "Handshake with SSL server failed: XYZ" where XYZ
is the corresponding error string/description returned by OpenSSL if
there is any.

This is a Measurement Factory project.