[8u] TLSv1.3 RFR: 8245474: Add TLS_KRB5 cipher suites support according to RFC-2712

[Martin Balao]

Hi Alexey,

While doing a final review to this Step, I found a missing check to
decide whether KRB5 key exchange mechanisms are available or not. Here
there are a few references to the check in the previous SunJSSE engine:
[1] [2] [3]. This is analogous to EC key exchange mechanisms in the new
SunJSSE engine [4] [5].

In addition, and given that we have finally co-authored this patch, I've
added a couple of copyright lines to KrbKeyExchange.java and
KrbClientKeyExchange.java files.

Webrev.05:

 * http://cr.openjdk.java.net/~mbalao/webrevs/8245474/8245474.webrev.05/

I'll commit this Step to the incubator repository (once review-approved
and previous steps are committed).

Thanks,
Martin.-

--
[1] -
http://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/84c5676f140b/src/share/classes/sun/security/ssl/CipherSuite.java#l373
[2] -
http://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/84c5676f140b/src/share/classes/sun/security/ssl/JsseJce.java#l58
[3] -
http://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/84c5676f140b/src/share/classes/sun/security/ssl/JsseJce.java#l197
[4] -
http://hg.openjdk.java.net/jdk-updates/jdk11u/file/d67b0f64be45/src/java.base/share/classes/sun/security/ssl/CipherSuite.java#l1070
[5] -
http://hg.openjdk.java.net/jdk-updates/jdk11u/file/d67b0f64be45/src/java.base/share/classes/sun/security/ssl/JsseJce.java#l174