RFR: 7903191: Fix build with "MAKEFLAGS=-j32". [v4]

[Jan Kratochvil]

> A parallel build needlessly errors out:

Jan Kratochvil has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:

  Fix build with "MAKEFLAGS=-j32".
  
  /bin/sh: line 5: jtreg/build/classes/com/sun/javatest/regtest/tool/jars.properties: No such file or directory
  make: *** [jtreg.gmk:98: jtreg/build/classes/com/sun/javatest/regtest/tool/jars.properties] Error 1

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Changes: https://git.openjdk.org/jtreg/pull/72/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=72&range=03
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jtreg/pull/72.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/72/head:pull/72

PR: https://git.openjdk.org/jtreg/pull/72