[jdk11u-dev] RFR: 8229147: Linux os::create_thread() overcounts guardpage size with newer glibc (>=2.27)

[Lutz Schmidt]

This backport is for parity with 11.0.21-oracle. 
Fix didn't apply at all, os/linux/os_linux.cpp was too different in particular. 
I managed to create a working version by massaging and applying the changes manually. 

There is some risk involved. It is not caused by the intentional change of behavior but by potential collateral damage. 

Reviews and tests are pending.
[Edit](https://bugs.openjdk.org/secure/EditComment!default.jspa?id=4997318&commentId=14594837)

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Commit messages:
 - Backport 9ebcda2165c42e3f7b82a9ae8074badb69c0d270

Changes: https://git.openjdk.org/jdk11u-dev/pull/2035/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2035&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8229147
  Stats: 148 lines in 3 files changed: 123 ins; 7 del; 18 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2035.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2035/head:pull/2035

PR: https://git.openjdk.org/jdk11u-dev/pull/2035