RFR: 8341246: Test com/sun/tools/attach/PermissionTest.java fails access denied after JDK-8327114 [v2]

[SendaoYan]

> Hi all,
> Test `com/sun/tools/attach/PermissionTest.java` fails access denied after [JDK-8327114](https://bugs.openjdk.org/browse/JDK-8327114). This testcase need the `readlink` permission of file `/proc/self/ns/mnt` after [JDK-8327114](https://bugs.openjdk.org/browse/JDK-8327114).
> So this PR add `readlink` permission to make this test work normally.
> Before this PR, test run failed, after this PR, test run success. Test fix only, no risk.

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

  merge two comments enclosed with /* ... */ on two lines

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21269/files
  - new: https://git.openjdk.org/jdk/pull/21269/files/f241371e..015d17cb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21269&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21269&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/21269.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21269/head:pull/21269

PR: https://git.openjdk.org/jdk/pull/21269