Throughout drop allow_ntsec and allow_smbntsec handling.

* environ.cc (set_ntsec): Remove.
	(set_smbntsec): Remove.
	(known): Remove ntsec and smbntsec options.
	* external.cc (check_ntsec): Return true if no filename is given.
	* mount.cc (oopts): Add "acl" and "noacl" options.  Set MOUNT_NOACL
	flag accordingly.
	(fillout_mntent): Handle MOUNT_NOACL flag.
	* path.h (enum path_types): Add PATH_NOACL.
	* security.cc (allow_ntsec): Remove.
	(allow_smbntsec): Remove.
	* security.h (allow_ntsec): Drop declaration.
	(allow_smbntsec): Drop declaration.
	* include/sys/mount.h (MOUNT_NOACL): Define.

winsup/cygwin/external.cc

@@ -123,9 +123,9 @@ static DWORD
 check_ntsec (const char *filename)
 {
   if (!filename)
-    return allow_ntsec;
+    return true;
   path_conv pc (filename);
-  return allow_ntsec && pc.has_acls ();
+  return pc.has_acls ();
 }
 
 /* Copy cygwin environment variables to the Windows environment. */