[8u] RFA+RFR (M) 8213952: Relax DNSName restriction as per RFC 1123

[Aleksey Shipilev]

Please review and approve 8u backport:

  Original Bug:
      URL: https://bugs.openjdk.java.net/browse/JDK-8213952
      Reporter: Sean Coffey
      Assignee: Sean Coffey
      Priority: P4
      Components: security-libs

  Original Fix:
        12: JDK-8213952, http://hg.openjdk.java.net/jdk/jdk/rev/5f3b9b633731, 78 day(s) ago

  Backports and Forwardports:
        11: 11.0.3, JDK-8219240, http://hg.openjdk.java.net/jdk-updates/jdk11u/rev/56d673a2ff47, 3
day(s) ago
         8: MISSING

The patch does not apply cleanly to jdk8u-dev, because it needs reshuffling and merges in comments.
Please review carefully. I eyeballed the original change vs. 8u version myself, but could use
another careful look.

8u webrev:
  http://cr.openjdk.java.net/~shade/8213952/webrev.01.8u/

Testing: new regression test, sun/security/tools/keytool tests, sun/security/x509/GeneralName tests

Thanks,
-Aleksey