JIT: fix assert when there are mixed types in Enum.HasFlags optimization

[AndyAyersMS]

In some cases the pre-boxed nodes may differ in type. Bail if they don't have
the same stack type, then compute the result using the stack type.

Extended the hasflags test with a case that shows this issue.

Closes #23847

[AndyAyersMS]

cc @dotnet/jit-contrib

Two diffs in FX where we now and/cmp int instead of short:

PMI Diffs for System.Private.CoreLib.dll, framework assemblies for x64 default jit
Summary:
(Lower is better)
Total bytes of diff: -8 (-0.00% of base)
    diff is an improvement.
Top file improvements by size (bytes):
          -8 : NuGet.LibraryModel.dasm (-0.04% of base)
1 total files with size differences (1 improved, 0 regressed), 128 unchanged.
Top method improvements by size (bytes):
          -4 (-0.73% of base) : NuGet.LibraryModel.dasm - LibraryDependencyTargetUtils:GetFlagString(ushort):ref
          -4 (-0.73% of base) : NuGet.LibraryModel.dasm - LibraryIncludeFlagUtils:GetFlagString(ushort):ref
Top method improvements by size (percentage):
          -4 (-0.73% of base) : NuGet.LibraryModel.dasm - LibraryDependencyTargetUtils:GetFlagString(ushort):ref
          -4 (-0.73% of base) : NuGet.LibraryModel.dasm - LibraryIncludeFlagUtils:GetFlagString(ushort):ref
2 total methods with size differences (2 improved, 0 regressed), 200142 unchanged.

[sandreenko]

LGTM

[AndyAyersMS]

CoreFX had one test timeout:

   System.Net.Security.Tests.SslStreamCredentialCacheTest.SslStream_SameCertUsedForClientAndServer_Ok [FAIL]
11:26:41       System.TimeoutException : Task timed out after 15000ms
``

[AndyAyersMS]

musl failure looks like some kind of CI issue:

  Job 11c4e90e-6213-45c1-9b0a-e3b0b5e6d62a is completed with 23 finished work items.
  Stopping Azure Pipelines Test Run Linux x64 Release no_tiered_compilation @ (Alpine.38.Amd64.Open)Ubuntu.1604.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.8-helix-45b1fa2-20190327215821
  Job d0675952-3aaf-4ccf-8e98-411f4437b7e4 is completed with 23 finished work items.
  Stopping Azure Pipelines Test Run Linux x64 Release @ (Alpine.38.Amd64.Open)Ubuntu.1604.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.8-helix-45b1fa2-20190327215821
/home/helixbot_azpcontainer/.nuget/packages/microsoft.dotnet.helix.sdk/2.0.0-beta.19210.7/tools/Microsoft.DotNet.Helix.Sdk.MultiQueue.targets(67,5): error : This task can only be used on completed jobs. There are 1 of 23 unfinished work items. [/__w/1/s/tests/helixpublishwitharcade.proj]

Build FAILED.

[echesakov]

musl failure looks like some kind of CI issue:
Job 11c4e90e-6213-45c1-9b0a-e3b0b5e6d62a is completed with 23 finished work items.
Stopping Azure Pipelines Test Run Linux x64 Release no_tiered_compilation @ (Alpine.38.Amd64.Open)Ubuntu.1604.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.8-helix-45b1fa2-20190327215821
Job d0675952-3aaf-4ccf-8e98-411f4437b7e4 is completed with 23 finished work items.
Stopping Azure Pipelines Test Run Linux x64 Release @ (Alpine.38.Amd64.Open)Ubuntu.1604.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.8-helix-45b1fa2-20190327215821
/home/helixbot_azpcontainer/.nuget/packages/microsoft.dotnet.helix.sdk/2.0.0-beta.19210.7/tools/Microsoft.DotNet.Helix.Sdk.MultiQueue.targets(67,5): error : This task can only be used on completed jobs. There are 1 of 23 unfinished work items. [/__w/1/s/tests/helixpublishwitharcade.proj]

Build FAILED.

@AndyAyersMS Yes, I suspect it's https://github.com/dotnet/core-eng/issues/5883

[AndyAyersMS]

Failures seem unrelated, so am going to merge this.