UefiCpuPkg: Extend SMM CPU Service with rendezvous support.

REF? https://bugzilla.tianocore.org/show_bug.cgi?id=3815

This patch define a new Protocol with the new services
SmmWaitForAllProcessor(), which can be used by SMI handler
to optionally wait for other APs to complete SMM rendezvous in
relaxed AP mode.

A new library SmmCpuRendezvousLib is provided to abstract the service
into library API to simple SMI handler code.

Cc: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Cc: Zhihao Li <zhihao.li@intel.com>

Signed-off-by: Zhihao Li <zhihao.li@intel.com>

UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf

@@ -4,7 +4,7 @@
 # This SMM driver performs SMM initialization, deploy SMM Entry Vector,
 # provides CPU specific services in SMM.
 #
-# Copyright (c) 2009 - 2021, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2009 - 2022, Intel Corporation. All rights reserved.<BR>
 # Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
 #
 # SPDX-License-Identifier: BSD-2-Clause-Patent
@@ -107,7 +107,8 @@
   gEfiSmmReadyToLockProtocolGuid           ## NOTIFY
   gEfiSmmCpuServiceProtocolGuid            ## PRODUCES
   gEdkiiSmmMemoryAttributeProtocolGuid     ## PRODUCES
-  gEfiMmMpProtocolGuid                    ## PRODUCES
+  gEfiMmMpProtocolGuid                     ## PRODUCES
+  gEdkiiSmmCpuRendezvousProtocolGuid       ## PRODUCES
 
 [Guids]
   gEfiAcpiVariableGuid                     ## SOMETIMES_CONSUMES ## HOB # it is used for S3 boot.