RFR: 8247690: RunTest does not support running of JTREG manual tests [v3]

[Matthew Donovan]

> This PR adds a make keyword, MANUAL, to run manual tests with the make command e.g.:
> 
> 
> make test JTREG=MANUAL=true TEST=... 
> 
> 
> I've gotten into the habit of running tests with make and although this doesn't come up often, I have wanted the functionality for a while.

Matthew Donovan has updated the pull request incrementally with one additional commit since the last revision:

  reverted to original change and updated testing.{md,html}

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28381/files
  - new: https://git.openjdk.org/jdk/pull/28381/files/1cfa515d..7cbb1ddb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28381&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28381&range=01-02

  Stats: 14 lines in 3 files changed: 13 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28381.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28381/head:pull/28381

PR: https://git.openjdk.org/jdk/pull/28381