RFR: 8333871: check sysinfo return values [v3]

[Matthias Baesken]

> In the review of [JDK-8333522](https://bugs.openjdk.org/browse/JDK-8333522) it has been discussed that we might run into issues because of failing sysinfo.
> However we miss checking the return values at some places, this might need adjustment.

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

  use more asserts

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28317/files
  - new: https://git.openjdk.org/jdk/pull/28317/files/e9d2b1b4..6284ef29

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28317&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28317&range=01-02

  Stats: 6 lines in 1 file changed: 2 ins; 4 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28317.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28317/head:pull/28317

PR: https://git.openjdk.org/jdk/pull/28317