JDK 11 RFR of 8194070 : Update various tests to pass under JDK 11

[joe darcy]

Hello,

Please review the changes to address

     8194070 : Update various tests to pass under JDK 11
     http://cr.openjdk.java.net/~darcy/8194070.2/

which are updates to the various and sundry multi-release jar files 
tests so that they can after both before and after the JDK version is 
updated from 10 to 11.

To summarize the changes, in different directories the multi-release jar 
files tests use the shared CreateMultiReleaseTestJars.java library. That 
library created fixed contents for versions 8, 9, and 10 in a 
multi-release jar files. Some tests looked for fixed contents in release 
8, 9, and 10, but also for content under Runtime.version().major(), or 
equivalent, which would stop working when the version went to 11. 
Therefore, some aspects of the overall testing of multi-release jar 
files was internally inconsistent.

This lead to the removal of the"-Djdk.util.jar.version=10" @run lines 
from MultiReleaseJarHttpProperties.java and MultiReleaseJarProperties.java.

I changed CreateMultiReleaseTestJars to created content for 8, 9, and 
the current version and made corresponding updates in the tests using 
the library. The general set of multi-release jar file tests could be 
made more comprehensive, but I'll leave that for, hopefully others to 
do, as future work.

The obvious delta to update MVJarSigningTest to JDK 11 did not create a 
working test; I'd prefer some one else track down which part of the 
supporting code also needs to be modified to work against the current 
version properly.

The changed tests pass under a current JDK 11 build as well as an 
internal JDK 11 build where the version has been updated to 11.

Thanks,

-Joe