RFR: 7904083: Print fatal error messages to stderr [v3]

[SendaoYan]

> Hi all,
> 
> Currently the fatal error message was print to stderr, shows as below. I think it's bettor to print the fatal error message to stderr.
> 
>> unset JAVA_HOME ; jtreg -version
> No java executable at java
> 
>> unset JAVA_HOME ; jtreg -version > /dev/null
> #nothing
> 
> The `>&2` usage for echo both works on linux and cygwin. I do not have other OS system to verify this change, but I think the risk of this change is low.

SendaoYan 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 three additional commits since the last revision:

 - Merge branch 'openjdk:master' into stderr
 - Merge branch 'openjdk:master' into stderr
 - 7904083: Print fatal error messages to stderr

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

Changes:
  - all: https://git.openjdk.org/jtreg/pull/290/files
  - new: https://git.openjdk.org/jtreg/pull/290/files/04d2135e..c03ca794

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=290&range=02
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=290&range=01-02

  Stats: 244 lines in 7 files changed: 195 ins; 23 del; 26 mod
  Patch: https://git.openjdk.org/jtreg/pull/290.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/290/head:pull/290

PR: https://git.openjdk.org/jtreg/pull/290