support creating new uts namespaces (and setting hostnames)

Bug: None
Test: `sudo ./minijail0 --uts=foo /bin/hostname` shows "foo"
Change-Id: Ibfd36fb64983413688fcbb58541b2aae3132df49
diff --git a/libminijail.h b/libminijail.h
index a1f2f74..08fdf2b 100644
--- a/libminijail.h
+++ b/libminijail.h
@@ -71,6 +71,8 @@
  */
 void minijail_skip_remount_private(struct minijail *j);
 void minijail_namespace_ipc(struct minijail *j);
+void minijail_namespace_uts(struct minijail *j);
+int minijail_namespace_set_hostname(struct minijail *j, const char *name);
 void minijail_namespace_net(struct minijail *j);
 void minijail_namespace_enter_net(struct minijail *j, const char *ns_path);
 void minijail_namespace_cgroups(struct minijail *j);