RFR: 7903765: wget failed in build.sh in jtreg

[andrlos]

Hi, this is a backport of the original https://github.com/openjdk/jtreg/pull/214 into the 6.1+x branch, since the branch is not currently buildable using make/build.sh script due to reasons in https://bugs.openjdk.org/browse/CODETOOLS-7903765

I also added jcov dependency fix for the same issue as part of the backport.

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Commit messages:
 - 7903765: wget failed in build.sh in jtreg

Changes: https://git.openjdk.org/jtreg/pull/234/files
  Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=234&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903765
  Stats: 14 lines in 4 files changed: 4 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jtreg/pull/234.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/234/head:pull/234

PR: https://git.openjdk.org/jtreg/pull/234