bpo-38109: Add missing constants to Lib/stat.py (GH-16665)

Add missing stat.S_IFDOOR, stat.S_IFPORT, stat.S_IFWHT,
stat.S_ISDOOR, stat.S_ISPORT, and stat.S_ISWHT values to
the Python implementation of the stat module.
diff --git a/Lib/test/test_stat.py b/Lib/test/test_stat.py
index 17443be..be01db2 100644
--- a/Lib/test/test_stat.py
+++ b/Lib/test/test_stat.py
@@ -16,10 +16,10 @@
                   'UF_IMMUTABLE', 'UF_NODUMP', 'UF_NOUNLINK', 'UF_OPAQUE'}
 
     formats = {'S_IFBLK', 'S_IFCHR', 'S_IFDIR', 'S_IFIFO', 'S_IFLNK',
-               'S_IFREG', 'S_IFSOCK'}
+               'S_IFREG', 'S_IFSOCK', 'S_IFDOOR', 'S_IFPORT', 'S_IFWHT'}
 
     format_funcs = {'S_ISBLK', 'S_ISCHR', 'S_ISDIR', 'S_ISFIFO', 'S_ISLNK',
-                    'S_ISREG', 'S_ISSOCK'}
+                    'S_ISREG', 'S_ISSOCK', 'S_ISDOOR', 'S_ISPORT', 'S_ISWHT'}
 
     stat_struct = {
         'ST_MODE': 0,
@@ -231,10 +231,6 @@
 class TestFilemodeCStat(TestFilemode, unittest.TestCase):
     statmod = c_stat
 
-    formats = TestFilemode.formats | {'S_IFDOOR', 'S_IFPORT', 'S_IFWHT'}
-    format_funcs = TestFilemode.format_funcs | {'S_ISDOOR', 'S_ISPORT',
-                                                'S_ISWHT'}
-
 
 class TestFilemodePyStat(TestFilemode, unittest.TestCase):
     statmod = py_stat