use tmp for install.jar to prevent confusion on build fails

[TITLE] so that somebody won't be like "the build failed but it produced the install jar what?"

not tested because noclassdef for pack200 because no pack200 for gentoo it's available in jdk:8, and tested.

Signed-off-by: AGentooCat agentoocat@mail.i2p

changed the description

added 7 commits

• 751e1f25...b5461f3b - 6 commits from branch i2p-hackers:master
• b96a5fe0 - Merge branch 'master' into add-tmp-to-install.jar

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requested review from @idk

assigned to @idk

approved this merge request

Tenatively approved, built and tested here.

merged

mentioned in commit 7d776889