RFR: JDK-8213214: Set -Djava.io.tmpdir= when running tests

[Erik Joelsson]

(re-sending this as it doesn't look like it was delivered)

There are a lot of jtreg tests that use temporary files. These temporary 
files add up over time and fill up the global temp directories on our 
test systems. To tackle this, we should try to redirect these temporary 
files into a directory controlled by the test framework. Jtreg does not 
do this, but we can set -Djava.io.tmpdir from RunTest.gmk. This will not 
prevent all temp files from being created outside of the work dir, but 
at least most.


I have found one test where this becomes an issue, 
java/nio/file/Path/Misc.java on Windows when running in elevated mode 
with the workspace on a subst drive. This looks like an actual issue in 
the product, so I have filed a separate bug for it [1]. Since we 
currently use subst in our distributed test system to get around Windows 
path length issues, we are hitting this problem. While the bug is being 
evaluated, I have implemented a workaround in the test so that it is 
able to handle the known situation. I would like to have someone from 
core-libs look at the workaround.

Webrev: http://cr.openjdk.java.net/~erikj/8213214/webrev.01/

Bug: https://bugs.openjdk.java.net/browse/JDK-8213214

/Erik

[1] https://bugs.openjdk.java.net/browse/JDK-8213216