RFR: JDK-8308872: enhance logging and some exception in krb5/Config.java [v2]

[Matthias Baesken]

> There exists already some logging in krb5/Config.java (enabled by -Dsun.security.krb5.debug=true), this could be enhanced for easier analysis of problems. Additionally some exception(s) might be slightly adjusted.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  enhance exception

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14151/files
  - new: https://git.openjdk.org/jdk/pull/14151/files/15ab2d27..74cdfe35

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14151&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14151&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14151.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14151/head:pull/14151

PR: https://git.openjdk.org/jdk/pull/14151