[8u] RFR 8209178: Proxied HttpsURLConnection doesn't send BODY when retrying POST request

[Zhengyu Gu]

Please review the 8u backport for parity with Oracle 8u331.

The JDK11u patch does not apply cleanly, but the only conflict is the 
copyright year line  of HttpClient.java.

However, the new test needs to be modified to run.

1) Removed module line.
2) Changed test library /test/lib => /lib/testlibrary
3) Changed library import as well jdk.test.lib.net.URIBuilder => 
jdk.testlibrary.net.URIBuilder


Bug: https://bugs.openjdk.java.net/browse/JDK-8209178
11u webrev: https://cr.openjdk.java.net/~vkempik/8209178/webrev.00/

8u webrev: http://cr.openjdk.java.net/~zgu/JDK-8209178-8u/webrev.00/

Test:
   New test passes.

Thanks,

-Zhengyu