[jdk8u-dev] RFR: 8295164: JDK8 jdi tests should not use tasklist command on Windows

[zzambers]

Shell jdi tests are currently failing on windows. These tests are part of jdk_tier1.

**Problem:**
Tests fail because ShellScaffold.sh uses (native) tasklist command to check if process with given PID is alive. However this no longer works, since PIDs by Cygwin/Msys2 are no longer same as native Windows PIDs [1][2].

**Solution:**
Fixed by switching to ps command. Original comment says tasklist was used due to ps sometimes missing some processes. This could be because ps, by default, only shows cygwin processes. I added -W argument to also show native windows processes [3] and I have seen no problems. Fix is targeted for JDK8, since newer JDKs migrated to java based tests (in several steps [4][5][6][7]...), but i think backporting all of that work, just to fix this issue would be overkill. (However nothing prevents anyone from doing so in the future, if desired.)

**Testing:**
With this fix jdk_tier1 passes for me on Windows.

[1] https://github.com/msys2/MSYS2-packages/issues/1724
[2] https://cygwin.com/git/?p=newlib-cygwin.git;a=commit;h=b5e1003722cb14235c4f166be72c09acdffc62ea
[3] https://www.cygwin.com/cygwin-ug-net/ps.html
[4] https://bugs.openjdk.org/browse/JDK-8209109
[5] https://bugs.openjdk.org/browse/JDK-8209604
[6] https://bugs.openjdk.org/browse/JDK-8210243
[7] https://bugs.openjdk.org/browse/JDK-8210760

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Commit messages:
 - ShellScaffold.sh should not use tasklist on windows

Changes: https://git.openjdk.org/jdk8u-dev/pull/133/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=133&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295164
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/133.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/133/head:pull/133

PR: https://git.openjdk.org/jdk8u-dev/pull/133