HttpsURLConnection fixes to pass URLConnectionTest and HttpsURLConnectionTest

    Add public getSecureSocket so that HttpsURLConnection can reset its sslSocket field on reused connections.

        luni/src/main/java/org/apache/harmony/luni/internal/net/www/protocol/http/HttpConnection.java

    discardIntermediateResponse now maintain old values for
    intermediateReponse, which is necessary when retrying the CONNECT
    method with proxy authorization.

        luni/src/main/java/org/apache/harmony/luni/internal/net/www/protocol/http/HttpURLConnectionImpl.java

    Clear sslSocket before retrying makeSslConnection to ensure we reconnect.
    makeSslConnection now resets sslSocket on resumed connection.
    makeSslConnection now exits early on existing connection.

        luni/src/main/java/org/apache/harmony/luni/internal/net/www/protocol/https/HttpsURLConnectionImpl.java

git cherry-pick -e 4df5be29bdffc09e7368c03423a0bef85fa26ac5
Bug: 3184701
Change-Id: Ida3c027f79e5e29968263ac761d4f4f79d063a27