RFR: 8273373: Zero: Handle thread stack sizes with a generic Linux code

[Aleksey Shipilev]

See the bug for more discussion.

Additional testing:
 - [x] Linux Zero x86_64 passes most gtests now (there are unrelated failures)
 - [x] Linux Zero x86_32 passes most gtests now (there are unrelated failures)

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Commit messages:
 - Fix

Changes: https://git.openjdk.java.net/jdk/pull/5376/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5376&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273373
  Stats: 88 lines in 2 files changed: 3 ins; 85 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5376.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5376/head:pull/5376

PR: https://git.openjdk.java.net/jdk/pull/5376