When running tests using "make run-test-prebuilt" on Windows, the
calculation of available memory may fail. This only happens on certain
systems, and is likely related to which version of Cygwin that is being
used. The consequence is that concurrency gets set to 1. The cause of
the problem is mishandling of Windows \r line endings, which Cygwin
tools are known to handle differently in different versions.
To fix the problem here, I've added explicit filtering of \r before
trying to interpret the memory size as a number.
I checked the corresponding construct in configure, and it seems to work
on the same machine where RunTestsPrebuilt.gmk failed, so I left it alone.
Bug: https://bugs.openjdk.java.net/browse/JDK-8216021
Webrev: http://cr.openjdk.java.net/~erikj/8216021/webrev.01/
/Erik
