SSL/TLS layer. http://www.mozilla.org/projects/security/pki/nss/

-fvisibility=hidden on gcc >= 4.0.  This reduces the size of the libcurl
binary and speeds up dynamic linking by hiding all the internal symbols from
the symbol table.

not supporting it. It hasn't been functioning for years anyway, so this is
just finally stating what already was true. And a cleanup at the same time.

document

short section

removed old section about problems with old autoconfs, I don't think that
happens anymore

windows build.