Pass a module reference to CloneModule.

It can never be null and most callers were already using references or
std::unique_ptr.

llvm-svn: 325160
diff --git a/llvm/lib/Transforms/Utils/SplitModule.cpp b/llvm/lib/Transforms/Utils/SplitModule.cpp
index 968eb02..7966fa4 100644
--- a/llvm/lib/Transforms/Utils/SplitModule.cpp
+++ b/llvm/lib/Transforms/Utils/SplitModule.cpp
@@ -270,7 +270,7 @@
   for (unsigned I = 0; I < N; ++I) {
     ValueToValueMapTy VMap;
     std::unique_ptr<Module> MPart(
-        CloneModule(M.get(), VMap, [&](const GlobalValue *GV) {
+        CloneModule(*M, VMap, [&](const GlobalValue *GV) {
           if (ClusterIDMap.count(GV))
             return (ClusterIDMap[GV] == I);
           else