prevent runtime shutdown while foreground threads keep running

[Rattenkrieg]

• [x] hack code
• [x] make GC_Scenarios._BinTree_thdtree_thdtree_._BinTree_thdtree_thdtree_sh, GC_Scenarios._BinTree_thdtreegrowingobj_thdtreegrowingobj_._BinTree_thdtreegrowingobj_thdtreegrowingobj_sh, GC_Scenarios._BinTree_thdtreelivingobj_thdtreelivingobj_._BinTree_thdtreelivingobj_thdtreelivingobj_sh green I have issues with ./tests/runtest.sh release -coreclr Top200 either hanging on these three or exiting with 134 code. When I run it manually by CORE_ROOT=./tests_downloaded/CoreCLR/Tests/Core_Root ./tests_downloaded/CoreCLR/GC/Scenarios/BinTree/thdtreegrowingobj/thdtreegrowingobj.sh everithing works fine. I guess I've introduced some threading issue to xUnit runners.
• [x] find some tests for foreground threads in CoreCLR or make our own

Simplified logic adopted from CoreCLR with no additional states like m_UnstartedThreadCount, m_PendingThreadCount etc.

[Rattenkrieg]

I guess we are done @jkotas

[jkotas]

This repo is getting archived soon. Would you mind to resubmit this PR against https://github.com/dotnet/runtimelab/tree/feature/NativeAOT ? I would have to manually port it and fix it up otherwise.

[jkotas]

The change looks great to me otherwise. Thank you!

[Rattenkrieg]

Thanks for your feedback!

This repo is getting archived soon. Would you mind to resubmit this PR against https://github.com/dotnet/runtimelab/tree/feature/NativeAOT ? I would have to manually port it and fix it up otherwise.

Sure. I think it will be convenient if I address your recent comments here and submit PR to runtimelab once it "LGTM".

[jkotas]

Yes, that's fine.

[jkotas]

Superseded by https://github.com/dotnet/runtimelab/pull/235