[Offload] Make MemoryManager threshold ENV var size_t type.

Author: hidekisaito

offload/include/Shared/EnvironmentVar.h

@@ -128,6 +128,7 @@ using Int32Envar = Envar<int32_t>;
 using Int64Envar = Envar<int64_t>;
 using UInt32Envar = Envar<uint32_t>;
 using UInt64Envar = Envar<uint64_t>;
+using SizeTEnvar = Envar<size_t>;
 using StringEnvar = Envar<std::string>;
 using BoolEnvar = Envar<bool>;
 

offload/plugins-nextgen/common/include/MemoryManager.h

@@ -324,7 +324,7 @@ class MemoryManagerTy {
   /// manager explicitly by setting the var to 0. If user doesn't specify
   /// anything, returns <0, true>.
   static std::pair<size_t, bool> getSizeThresholdFromEnv() {
-    static UInt32Envar MemoryManagerThreshold(
+    static SizeTEnvar MemoryManagerThreshold(
         "LIBOMPTARGET_MEMORY_MANAGER_THRESHOLD", 0);
 
     size_t Threshold = MemoryManagerThreshold.get();