Incorrect state machine compilation in debug

[majocha]

Please provide a succinct description of the issue.

Repro steps

1. Clone https://github.com/fsprojects/FSharp.Control.TaskSeq
2. just run smoke tests in VS test explorer or:
   edit sdk pin in global.json to "10.0.400"
   dotnet test -c Debug .\src\FSharp.Control.TaskSeq.SmokeTests\
   builds fine, runs fine, taskSeq produces wrong values and tests fail.

This is particularly nasty, because it builds and runs, just the execution is wrong.

Tests pass up to sdk 10.0.204, fail for 10.0.400 and 11 preview.

[majocha]

Large part of it is that TaskSeq's dynamic implementation is incomplete and untested. Up til recently we emitted the static implementation even in debug, so this was hidden and not exercised unless a consumer wrote code that did not statically compile.

[T-Gro]

<OtherFlags>--always-inline+</OtherFlags> should help in the meantime.

I would also love if we could have an addition to the regression testing matrix guarding TaskSeq.