Current vmTestbase/gc/g1/unloading tests contain 112 tests, each running exclusively. This drags the tier4 test times up. There seem to be no reason to run these tests exclusively, though: they complete in reasonable time, are lightly-threaded, and consume the usual amount of memory.

We should consider enabling parallelism for them and get improved test performance. Currently it is blocked by TEST.properties with exclusiveAccess.dirs directives in them.

Current run on 16-core machine:
 4340.46s user 107.99s system 128% cpu 57:37.79 total

Fully parallel:
 4138.37s user 84.50s system 808% cpu 8:42.62 total