Migrate the last remaining test to the new test framework.
Migrate the last remaining test to the new test framework.

* test/test_context.c
  (proxy_digest_authn_callback): Match realm using actual host/port.
  (test_ssltunnel_digest_auth): Rewrite using mock server/proxy and macro's.
  (test_ssltunnel_spnego_authn): Fix comment.
  (test_context): Reorder tests.

x-clone/serf,zhengcq315/serf,zhupan/serf,SirJson/serf,stoneCC/serf,pengdu/serf,SirJson/serf,google-code-export/serf,stoneCC/serf,google-code-export/serf,zhupan/serf,zhengcq315/serf,soufianeEL/serf,SirJson/serf,yesoce/serf,SirJson/serf,alex1818/serf,google-code-export/serf,KyleSanderson/serf,yesoce/serf,yesoce/serf,soufianeEL/serf,x-clone/serf,pengdu/serf,lazysoez/serf,stoneCC/serf,pengdu/serf,zhengcq315/serf,KyleSanderson/serf,lazysoez/serf,zhupan/serf,alex1818/serf,soufianeEL/serf,zhengcq315/serf,soufianeEL/serf,pengdu/serf,google-code-export/serf,alex1818/serf,alex1818/serf,x-clone/serf,KyleSanderson/serf,yesoce/serf,KyleSanderson/serf,lazysoez/serf,zhupan/serf,lazysoez/serf,x-clone/serf,stoneCC/serf