Don't bother with chmod() on Windows

It's fairly pointles to play with Unix rwxrwxrwx modes on Windows. One
never knows for sure how some emulation layer (Python's in this case)
guesstimates and mishandles the conversion to Windows ACLs. Not doing
them on Windows unbrokw the nss build. For me at least.

Change-Id: Id3a2f1755cd6f64bd681a3b4cb7f3c7abd3aa5b7

nss/nsinstall.py

@@ -103,7 +103,7 @@ def nsinstall(argv):
       if not os.path.isdir(args[0]):
         sys.stderr.write('nsinstall: ' + args[0] + ' is not a directory\n')
         sys.exit(1)
-      if options.m:
+      if os.name != 'nt' and options.m:
         os.chmod(args[0], options.m)
       sys.exit()
     if options.m:
@@ -121,7 +121,7 @@ def nsinstall(argv):
       dest = os.path.join(target,
                           os.path.basename(os.path.normpath(e)))
       handleTarget(e, dest)
-      if options.m:
+      if os.name != 'nt' and options.m:
         os.chmod(dest, options.m)
 
   # set up handler
@@ -139,7 +139,7 @@ def nsinstall(argv):
         entries = [os.path.join(srcpath, e) for e in os.listdir(srcpath)]
         copy_all_entries(entries, targetpath)
         # options.t is not relevant for directories
-        if options.m:
+        if os.name != 'nt' and options.m:
           os.chmod(targetpath, options.m)
       elif options.t:
         if os.path.exists(targetpath):