RFR: 8224665: Parallel GC: Use WorkGang (7: remove task manager)

[Leo Korinth]

Hi,

Here is the seventh patch in a proposed patch series of eight that
removes gcTaskManager and uses the WorkGang abstraction instead.

We try to remove everything task manager and task thread related.

Some utility methods (gc_threads_do, print_gc_threads_on) are changed
to use the WorkGang versions. Some worker counts are fetched from
WorkGang as well. Most of the change is just code deletion.

Enhancement:
   https://bugs.openjdk.java.net/browse/JDK-8224665

Webrev:
 
http://cr.openjdk.java.net/~lkorinth/workgang/0/_8224665-Parallel-GC-Use-WorkGang-7-remove-task-manager/
   http://cr.openjdk.java.net/~lkorinth/workgang/0/all/

Testing (on the whole patch series):
   mach5 remote-build-and-test --build-profiles 
linux-x64,linux-x64-debug,macosx-x64,solaris-sparcv9,windows-x64 --test 
open/test/hotspot/jtreg/:hotspot_gc -a -XX:+UseParallelGC
   gc test suite

Thanks,
Leo