RFR: 7903601 : jtr.xml logs produced with -xml argument do not contain failure justification [v2]

[andrlos]

> issue:
> https://bugs.openjdk.org/browse/CODETOOLS-7903601
> 
> with "-xml" argument when a shell driven test fails, the only thing you are getting in jtr.xml file as an explanation is the exit code which is not very helpful.. this is a fix for that which aligns the behavior of shell tests with that of java tests. The solution is up for a discussion, I just did the simplest and sturdiest solution I could think of.. in case there is no "main" section in the original jtr file, the xmlwriter in jtreg tries to iterate the sections again for "shell" section and writes the failure it finds there to the jtr.xml log

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

  fix based on PR comments

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

Changes:
  - all: https://git.openjdk.org/jtreg/pull/175/files
  - new: https://git.openjdk.org/jtreg/pull/175/files/3916e384..a3e95cc6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=175&range=01
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=175&range=00-01

  Stats: 8 lines in 1 file changed: 0 ins; 2 del; 6 mod
  Patch: https://git.openjdk.org/jtreg/pull/175.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/175/head:pull/175

PR: https://git.openjdk.org/jtreg/pull/175