RFR: 8295229: Try to verify gtest version [v2]

[Magnus Ihse Bursie]

> Inspired by the comment https://github.com/openjdk/jdk/pull/10503#issuecomment-1275500585 for JDK-8294623, I realized we need to do at least some kind of version verification of gtest.
> 
> Since gtest do not properly declare its version, this can't be done exactly, but we can look at some tell-tales and rule out versions that are way too far off.
> 
> I also updated the testing documentation to point to the build information about how to point to the gtest source, and the version requirements.

Magnus Ihse Bursie has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into try-verify-gtest-version
 - 8295229: Try to verify gtest version

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10677/files
  - new: https://git.openjdk.org/jdk/pull/10677/files/81b7e4c9..9e0366a6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10677&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10677&range=00-01

  Stats: 241 lines in 31 files changed: 139 ins; 23 del; 79 mod
  Patch: https://git.openjdk.org/jdk/pull/10677.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10677/head:pull/10677

PR: https://git.openjdk.org/jdk/pull/10677