Skip test_rm_r_no_permissions test under root

Skip the test_rm_r_no_permissions test under the root user, as deletion always succeeds.

Signed-off-by: Jiaying Song <[email protected]>

Author: jiajia123-wind

test/fileutils/test_fileutils.rb

@@ -769,7 +769,7 @@ def test_rm_r_pathname
   def test_rm_r_no_permissions
     check_singleton :rm_rf
 
-    return if /mswin|mingw/ =~ RUBY_PLATFORM
+    return if root_in_posix?
 
     mkdir 'tmpdatadir'
     touch 'tmpdatadir/tmpdata'