Remove Win32 readlink() code.

Windows symlinks really aren't meant to be treated like Unix symlinks, and we don't support creating symlinks anyway, so we don't even know if this code works...

c++/src/kj/filesystem-disk-win32.c++

@@ -696,39 +696,12 @@ public:
   }
 
   Maybe<String> tryReadlink(PathPtr path) {
-    HANDLE newHandle;
-    KJ_WIN32_HANDLE_ERRORS(newHandle = CreateFileW(
-        nativePath(path).begin(),
-        GENERIC_READ,
-        FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
-        NULL,
-        OPEN_EXISTING,
-        FILE_FLAG_OPEN_REPARSE_POINT,
-        NULL)) {
-      case ERROR_FILE_NOT_FOUND:
-      case ERROR_PATH_NOT_FOUND:
-        return nullptr;
-      default:
-        KJ_FAIL_WIN32("CreateFile(symlinkPath, OPEN_EXISTING)", error, path) { return nullptr; }
-    }
-
-    kj::AutoCloseHandle ownHandle(newHandle);
-
-    auto buffer = kj::heapArray<byte>(MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
-    DWORD actualSize;
-    KJ_WIN32(DeviceIoControl(
-        ownHandle, FSCTL_GET_REPARSE_POINT, NULL, 0, buffer.begin(), buffer.size(),
-        &actualSize, NULL));
-
-    auto msReparse = reinterpret_cast<REPARSE_DATA_BUFFER*>(buffer.begin());
-    KJ_REQUIRE(msReparse->ReparseTag == IO_REPARSE_TAG_SYMLINK, "not a symlink", path);
-
-    auto& symlink = msReparse->SymbolicLinkReparseBuffer;
-
-    auto start = symlink.PathBuffer + symlink.SubstituteNameOffset / sizeof(WCHAR);
-    auto end = start + symlink.SubstituteNameLength / sizeof(WCHAR);
-
-    return decodeWideString(arrayPtr(start, end));
+    // Windows symlinks work differently from Unix. Generally they are set up by the system
+    // administrator and apps are expected to treat them transparently. Hence, on Windows, we act
+    // as if nothing is a symlink by always returning null here.
+    // TODO(someday): If we want to treat Windows symlinks more like Unix ones, start by reverting
+    //   the comment that added this comment.
+    return nullptr;
   }
 
   // Directory -----------------------------------------------------------------