init: Fix mkdir command when using ISUID or ISGID bit

On first boot, the directory is created with root:root ownership and
then chowned. chown clears the ISUID and ISGID bits, so we need to chmod
the directory again after chown.

Change-Id: I02dfe7a19a637678256b4e7cc09e6b5431e6f11e

init/builtins.c

@@ -322,6 +322,14 @@ int do_mkdir(int nargs, char **args)
         if (_chown(args[1], uid, gid) < 0) {
             return -errno;
         }
+
+        /* chown may have cleared S_ISUID and S_ISGID, chmod again */
+        if (mode & (S_ISUID | S_ISGID)) {
+            ret = _chmod(args[1], mode);
+            if (ret == -1) {
+                return -errno;
+            }
+        }
     }
 
     return 0;