MdeModulePkg Variable: Introduce PcdReclaimVariableSpaceAtEndOfDxe

for trying to reclaim variable space at EndOfDxe.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16687 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c

@@ -3124,6 +3124,15 @@ ReclaimForOS(
   EFI_STATUS                     Status;
   UINTN                          RemainingCommonRuntimeVariableSpace;
   UINTN                          RemainingHwErrVariableSpace;
+  STATIC BOOLEAN                 Reclaimed;
+
+  //
+  // This function will be called only once at EndOfDxe or ReadyToBoot event.
+  //
+  if (Reclaimed) {
+    return;
+  }
+  Reclaimed = TRUE;
 
   Status  = EFI_SUCCESS;