Win32 API invoked on macOS

[filipnavara]

The OSX10.12 Debug and CoreFX tests job in PR #6955 failed with the following error:

08:46:04 xUnit.net console test runner (64-bit .NET Core)
08:46:04 Copyright (C) 2014 Outercurve Foundation.
08:46:04 
08:46:04 Discovering: System.Collections.Tests
08:46:05 Discovered:  System.Collections.Tests
08:46:05 Starting:    System.Collections.Tests
08:46:06 Unhandled Exception: EETypeRva:0x017EDFF8: 
08:46:06    at xunit.console!<BaseAddress>+0x7940c1
08:46:06    at xunit.console!<BaseAddress>+0x6fe667
08:46:06    at System.Diagnostics.StackTrace..ctor(Int32, Boolean) + 0x8f
08:46:06    at System.Diagnostics.DebugProvider.Fail(String, String) + 0x4d
08:46:06    at System.Diagnostics.Debug.Fail(String, String) + 0x45
08:46:06    at System.Diagnostics.Debug.Assert(Boolean, String, String) + 0x43
08:46:06    at System.Diagnostics.Debug.Assert(Boolean) + 0x28
08:46:06    at xunit.console!<BaseAddress>+0x688755
08:46:06    at xunit.console!<BaseAddress>+0x7c6608
08:46:06    at xunit.console!<BaseAddress>+0x79f36b
08:46:06    at xunit.console!<BaseAddress>+0x79ebc7
08:46:06    at xunit.console!<BaseAddress>+0x79e9b6
08:46:06    at xunit.console!<BaseAddress>+0x7c6281
08:46:06    at xunit.console!<BaseAddress>+0x6943f3
08:46:06    at xunit.console!<BaseAddress>+0x68b879
08:46:06    at xunit.console!<BaseAddress>+0x6a718a
08:46:06    at xunit.console!<BaseAddress>+0x6a7351
08:46:06    at xunit.console!<BaseAddress>+0x68bac5
08:46:06    at xunit.console!<BaseAddress>+0x6c2ae8
08:46:06    at xunit.console!<BaseAddress>+0x6c247f
08:46:06    at xunit.console!<BaseAddress>+0x6b3b3b
08:46:06    at xunit.console!<BaseAddress>+0x90ea54
08:46:06    at System.Threading.Tasks.TaskFactory`1.StartNew(Func`1, CancellationToken, TaskCreationOptions, TaskScheduler) + 0x6c
08:46:06    at System.Threading.Tasks.Task.Run[TResult](Func`1, CancellationToken) + 0xcc
08:46:06    at Xunit.Sdk.XunitTestAssemblyRunner.<>c__DisplayClass14_0.<RunTestCollectionsAsync>b__1(Func`1) + 0x3f
08:46:06    at Xunit.Sdk.XunitTestAssemblyRunner.<>c__DisplayClass14_0.<RunTestCollectionsAsync>b__2(Tuple`2) + 0xae
08:46:06    at xunit.console!<BaseAddress>+0x865cb7
08:46:06    at xunit.console!<BaseAddress>+0x7ea9b9
08:46:06    at xunit.console!<BaseAddress>+0xa50eea
08:46:06    at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1) + 0x82
08:46:06    at Xunit.Sdk.XunitTestAssemblyRunner.<RunTestCollectionsAsync>d__14.MoveNext() + 0x359
08:46:06    at xunit.console!<BaseAddress>+0xa8a25a
08:46:06    at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.Start[TStateMachine](TStateMachine&) + 0x1f
08:46:06    at Xunit.Sdk.XunitTestAssemblyRunner.RunTestCollectionsAsync(IMessageBus, CancellationTokenSource) + 0x8d
08:46:06    at Xunit.Sdk.TestAssemblyRunner`1.<RunAsync>d__41.MoveNext() + 0x320
08:46:06    at xunit.console!<BaseAddress>+0xa90aa9
08:46:06    at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.Start[TStateMachine](TStateMachine&) + 0x34
08:46:06    at Xunit.Sdk.TestAssemblyRunner`1.RunAsync() + 0x7b
08:46:06    at Xunit.Sdk.XunitTestFrameworkExecutor.<RunTestCases>d__6.MoveNext() + 0xc0
08:46:06    at xunit.console!<BaseAddress>+0xa8c91a
08:46:06    at System.Runtime.CompilerServices.AsyncVoidMethodBuilder.Start[TStateMachine](TStateMachine&) + 0x1b
08:46:06    at Xunit.Sdk.XunitTestFrameworkExecutor.RunTestCases(IEnumerable`1, IMessageSink, ITestFrameworkExecutionOptions) + 0xa8
08:46:06    at Xunit.Sdk.TestFrameworkExecutor`1.RunTests(IEnumerable`1, IMessageSink, ITestFrameworkExecutionOptions) + 0x98
08:46:06    at Xunit.Xunit2.RunTests(IEnumerable`1, IMessageSink, ITestFrameworkExecutionOptions) + 0x3d
08:46:06    at Xunit.XunitFrontController.RunTests(IEnumerable`1, IMessageSink, ITestFrameworkExecutionOptions) + 0x4c
08:46:06    at Xunit.ConsoleClient.Program.ExecuteAssembly(Object, String, XunitProjectAssembly, Boolean, Boolean, Boolean, Boolean, Nullable`1, Nullable`1, ExtendedXunitFilters) + 0x7d6
08:46:06    at Xunit.ConsoleClient.Program.RunProject(String, ExtendedXunitProject, Boolean, Boolean, Boolean, Nullable`1, Nullable`1, Nullable`1) + 0x59b
08:46:06    at Xunit.ConsoleClient.Program.Main(String[]) + 0x3ad
08:46:06    at xunit.console!<BaseAddress>+0xa4c2ff
08:46:06    at xunit.console!<BaseAddress>+0xa4c381
08:46:06 
08:46:07 Finished:    System.Collections.Tests
08:46:07 System.DllNotFoundException: Unable to load DLL 'api-ms-win-core-kernel32-legacy-l1-1-0.dll': The specified module could not be found.

The Assert failure is likely something broken in the PR, but the call to PInvoke_RaiseFailFastException (src/System.Private.CoreLib/src/Interop/Interop.manual.cs) on non-Windows system is likely something broken.