Fix setting creation date for OSX - revert windows changes & simplify code

Revert the changes for Windows & disable the SettingUpdatesPropertiesOnSymlink test on Windows.
Remove unnecessary setting to 0 on the attrList variable.
Remove the unnecessary MarshalAs attributes in the AttrList type.

Fix for #39132 and issues in #49555.

Author: hamarb123

src/libraries/Common/src/Interop/OSX/Interop.libc.cs

@@ -11,13 +11,13 @@ internal static partial class libc
         [StructLayout(LayoutKind.Sequential)]
         internal struct AttrList
         {
-            [MarshalAs(UnmanagedType.U2)] public ushort bitmapCount;
-            [MarshalAs(UnmanagedType.U2)] public ushort reserved;
-            [MarshalAs(UnmanagedType.U4)] public uint commonAttr;
-            [MarshalAs(UnmanagedType.U4)] public uint volAttr;
-            [MarshalAs(UnmanagedType.U4)] public uint dirAttr;
-            [MarshalAs(UnmanagedType.U4)] public uint fileAttr;
-            [MarshalAs(UnmanagedType.U4)] public uint forkAttr;
+            public ushort bitmapCount;
+            public ushort reserved;
+            public uint commonAttr;
+            public uint volAttr;
+            public uint dirAttr;
+            public uint fileAttr;
+            public uint forkAttr;
 
             public const ushort ATTR_BIT_MAP_COUNT = 5;
             public const uint ATTR_CMN_CRTIME = 0x00000200;

src/libraries/Common/src/Interop/Windows/Kernel32/Interop.FileOperations.cs

@@ -19,7 +19,6 @@ internal partial class FileOperations
             internal const int FILE_FLAG_BACKUP_SEMANTICS = 0x02000000;
             internal const int FILE_FLAG_FIRST_PIPE_INSTANCE = 0x00080000;
             internal const int FILE_FLAG_OVERLAPPED = 0x40000000;
-            internal const int FILE_FLAG_OPEN_REPARSE_POINT = 0x00200000;
 
             internal const int FILE_LIST_DIRECTORY = 0x0001;
         }

src/libraries/System.IO.FileSystem/src/System/IO/FileStatus.OSX.cs

@@ -22,12 +22,7 @@ internal unsafe void SetCreationTime(string path, DateTimeOffset time)
 
             Interop.libc.AttrList attrList = default;
             attrList.bitmapCount = Interop.libc.AttrList.ATTR_BIT_MAP_COUNT;
-            attrList.reserved = 0;
             attrList.commonAttr = Interop.libc.AttrList.ATTR_CMN_CRTIME;
-            attrList.dirAttr = 0;
-            attrList.fileAttr = 0;
-            attrList.forkAttr = 0;
-            attrList.volAttr = 0;
 
             // Try to set the attribute on the file system entry using setattrlist,
             // otherwise fall back to the method used on other unix platforms as the

src/libraries/System.IO.FileSystem/src/System/IO/FileSystem.Windows.cs

@@ -158,7 +158,7 @@ private static SafeFileHandle OpenHandle(string fullPath, bool asDirectory)
                 Interop.Kernel32.GenericOperations.GENERIC_WRITE,
                 FileShare.ReadWrite | FileShare.Delete,
                 FileMode.Open,
-                (asDirectory ? Interop.Kernel32.FileOperations.FILE_FLAG_BACKUP_SEMANTICS : 0) | Interop.Kernel32.FileOperations.FILE_FLAG_OPEN_REPARSE_POINT);
+                asDirectory ? Interop.Kernel32.FileOperations.FILE_FLAG_BACKUP_SEMANTICS : 0);
 
             if (handle.IsInvalid)
             {

src/libraries/System.IO.FileSystem/tests/Base/BaseGetSetTimes.cs

@@ -111,7 +111,7 @@ public void SettingUpdatesPropertiesAfterAnother()
         }
 
         [Fact]
-        [PlatformSpecific(~TestPlatforms.Browser)]
+        [PlatformSpecific(~(TestPlatforms.Browser | TestPlatforms.Windows))]
         public void SettingUpdatesPropertiesOnSymlink()
         {
             // This test makes sure that the times are set on the symlink itself.