8215449: Several tests failing when jtreg run with -vmoption:--illegal-access=deny

[Alan Bateman]

This is test only change to fix a few tests that don't have complete 
@modules or --add-exports options and so fail when running jtreg with 
vmoption:--illegal-access=deny.

The only change that might not be obvious is to 
langtools/tools/javac/platform/CanHandleClassFilesTest.java. That test 
creates a custom class loader to load the CreateSymbols tool from the 
make tree. jtreg doesn't know how to export packages to the unnamed 
module of custom class loaders so the test is changed to open the 
packages to the test and then pass on the rights to the unnamed module 
of the custom class loader.

http://cr.openjdk.java.net/~alanb/8215449/webrev/index.html

-Alan