file(INSTALL): Fix file ownership regression when running as root on macOS

Backport KWSys commit `51272e80e` (SystemTools: Avoid macOS copyfile
semantic differences as root, 2023-03-07).

Fixes: #24577

Source/kwsys/SystemTools.cxx

@@ -2483,6 +2483,12 @@ Status SystemTools::CloneFileContent(std::string const& source,
   return status;
 #elif defined(__APPLE__) &&                                                   \
   defined(KWSYS_SYSTEMTOOLS_HAVE_MACOS_COPYFILE_CLONE)
+  // When running as root, copyfile() copies more metadata than we
+  // want, such as ownership.  Pretend it is not available.
+  if (getuid() == 0) {
+    return Status::POSIX(ENOSYS);
+  }
+
   // NOTE: we cannot use `clonefile` as the {a,c,m}time for the file needs to
   // be updated by `copy_file_if_different` and `copy_file`.
   if (copyfile(source.c_str(), destination.c_str(), nullptr,