Integrated: 7903154: jextract build fails on Windows

[Athijegannathan Sundararajan]

Apart from quote issue for --add-options, @mcimadamore found that the verify target failed as well. "jextract.bat" has to be launched on Windows (instead of "jextract")

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Commit messages:
 - 7903154: jextract build fails on Windows

Changes: https://git.openjdk.java.net/jextract/pull/18/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jextract&pr=18&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7903154
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jextract/pull/18.diff
  Fetch: git fetch https://git.openjdk.java.net/jextract pull/18/head:pull/18

PR: https://git.openjdk.java.net/jextract/pull/18