RFR: 8272124: Cgroup v1 initialization causes NullPointerException when path contains colon [v2]

[Harold Seigel]

> Please review this small fix for JDK-8272124.  The fix puts a limit of 3 when splitting self cgroup lines by ':' so that Cgroup paths won't get truncated if they contain embedded ':'s.  For example, an entry of "11:memory:/user.sli:ce" in a /proc/self/cgroup file will now result in a Cgroup path of "/user.sli:ce" instead of "/user.sli".
> 
> The fix was tested with Mach5 tiers 1 and 2, and Mach5 tiers 3-5 on Linux x64 and Linux aarch64.
> 
> Thanks, Harold

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

  add test case, comments, and other small changes

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5127/files
  - new: https://git.openjdk.java.net/jdk/pull/5127/files/918df2b4..5fa37e97

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5127&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5127&range=00-01

  Stats: 41 lines in 2 files changed: 36 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5127.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5127/head:pull/5127

PR: https://git.openjdk.java.net/jdk/pull/5127