[jdk11u-dev] RFR: 8269025: jsig/Testjsig.java doesn't check exit code

[Andrew Lu]

I backport this for parity with 11.0.23-oracle.

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Commit messages:
 - Backport 60389eedb3c9932de57aca740a8116db83302ffa

Changes: https://git.openjdk.org/jdk11u-dev/pull/2421/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2421&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8269025
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2421.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2421/head:pull/2421

PR: https://git.openjdk.org/jdk11u-dev/pull/2421