[ORC] Use MapperJITLinkMemoryManager for ReOptimizeLayerTest. (llvm#163495)

This is an attempted fix for
llvm#158270.

The issue described sounds like it may be caused by non-contiguous
regions returned for separate allocations by the default memory manager.
Using MapperJITLinkMemoryMnaager with a 10Mb slab size should fix the
issue.

Author: lhames

llvm/unittests/ExecutionEngine/Orc/ReOptimizeLayerTest.cpp

@@ -9,6 +9,7 @@
 #include "llvm/ExecutionEngine/Orc/IRTransformLayer.h"
 #include "llvm/ExecutionEngine/Orc/JITLinkRedirectableSymbolManager.h"
 #include "llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h"
+#include "llvm/ExecutionEngine/Orc/MapperJITLinkMemoryManager.h"
 #include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
 #include "llvm/ExecutionEngine/Orc/ObjectTransformLayer.h"
 #include "llvm/ExecutionEngine/Orc/SelfExecutorProcessControl.h"
@@ -84,8 +85,11 @@ class ReOptimizeLayerTest : public testing::Test {
 
     ES = std::make_unique<ExecutionSession>(std::move(*EPC));
     JD = &ES->createBareJITDylib("main");
+
     ObjLinkingLayer = std::make_unique<ObjectLinkingLayer>(
-        *ES, std::make_unique<InProcessMemoryManager>(*PageSize));
+        *ES, std::make_unique<MapperJITLinkMemoryManager>(
+                 10 * 1024 * 1024,
+                 std::make_unique<InProcessMemoryMapper>(*PageSize)));
     DL = std::make_unique<DataLayout>(std::move(*DLOrErr));
 
     auto TM = JTMB->createTargetMachine();