Reverts https://github.com/dotnet/corefx/pull/37583 ("Use clonefile for CopyFile, if available #37583")

[jozkee]

Fixes #31429
We will bring back the reverted change on 6.0 and ensure that doesn't regress functionality

[carlossanlop]

cc @filipnavara

[carlossanlop]

Thanks for making the change, @jozkee. It looks good, let's wait for the CI results.

[carlossanlop]

The WASM CI leg failed with errors that seem related to this change:

[20:10:22] dbug: test[0]
      [FAIL] System.IO.Tests.FileInfo_CopyTo_str_b.CopyFileWithData(data: [], readOnly: False)
[20:10:22] dbug: test[0]
      [FAIL] System.IO.Tests.FileInfo_CopyTo_str_b.CopyFileWithData(data: [0x008f], readOnly: False)
[20:10:23] dbug: test[0]
      [FAIL] System.IO.Tests.FileInfo_CopyTo_str_b.CopyFileWithData(data: ['D', '¢', 'Y', 0x009c, 'é', ...], readOnly: False)
[20:10:23] dbug: test[0]
      [FAIL] System.IO.Tests.FileInfo_CopyTo_str_b.CopyFileWithData(data: ['ö', 0x0080, '\r', '×', 'Ö', ...], readOnly: False)
[20:10:27] dbug: test[0]
      [FAIL] System.IO.Tests.FileInfo_CopyTo_str_b.CopyFileWithData(data: ['3', 'F', 'ÃŽ', 0x008e, 0x000e, ...], readOnly: False)
...
...

[safern]

@steveisok this seems related to the tests we just enabled? Could you help @jozkee here? Should we open an issue and disable the tests and then in 6.0 enable them once we have this fix in? cc: @lewing

[steveisok]

Hmm - I think something / somethings in copy may be broken with this change. Unfortunately, we need to look closer to be able to tell.

[steveisok]

Actually, the failures are Assert.InRange() Failure\r\nRange: (08/13/2020 08:08:37 - 08/13/2020 08:08:39)\r\nActual: 08/13/2020 07:08:38. Is this branch behind master to some degree?

[jozkee]

@steveisok I just merged with master but seems that the Assert.InRange failure persists.

A new test added on this PR also fails for wasm:

[22:39:38] dbug: test[0]
      [FAIL] System.IO.Tests.File_Copy_Single.EnsureThrowWhenCopyToNonSharedFile
      
[22:39:38] dbug: test[0]
      Assert.Throws() Failure
      
[22:39:38] dbug: test[0]
      Expected: typeof(System.IO.IOException)
      
[22:39:38] dbug: test[0]
      Actual:   (No exception was thrown)

Is this something that we could defer to RC2?
@danmosemsft @jeffhandley

[steveisok]

I say disable the tests and we can take a closer look.

[jozkee]

Current CI issues are unrelated:
#40881
#11063