RFR: 8356997: /etc/krb5.conf parser should not forbid include/includedir directives after sections [v2]

[Weijun Wang]

> Several changes are made:
> 
> 1. The "include" and "includedir" directives can appear everywhere, even inside a section or a sub-section. However, it only means the content is inserted here but the included file still need its own full structure -- from section to subsections.
> 2. The same file can be included multiple times as long as not recursively.
> 3. Everything is merged. For duplicated values, `get` returns the first one and `getAll` returns all joining by spaces.
> 
> Two new tests added. I also separately confirmed that they are parsed in the same way as [MIT krb5](https://github.com/krb5/krb5/blob/master/src/util/profile/test_parse.c). MIT krb5 ignores directory name after "include" but here it's an error.

Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:

  more random testing

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/25421/files
  - new: https://git.openjdk.org/jdk/pull/25421/files/9ab72006..dfabb82a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25421&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25421&range=00-01

  Stats: 42 lines in 1 file changed: 23 ins; 4 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/25421.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25421/head:pull/25421

PR: https://git.openjdk.org/jdk/pull/25421