Add doInitialization/doFinalization to DataLayoutPass.

With this a DataLayoutPass can be reused for multiple modules.

Once we have doInitialization/doFinalization, it doesn't seem necessary to pass
a Module to the constructor.

Overall this change seems in line with the idea of making DataLayout a required
part of Module. With it the only way of having a DataLayout used is to add it
to the Module.

llvm-svn: 217548
diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index f8172b5..f1a945a 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -440,7 +440,7 @@
   }
 
   if (DL)
-    Passes.add(new DataLayoutPass(M.get()));
+    Passes.add(new DataLayoutPass());
 
   Triple ModuleTriple(M->getTargetTriple());
   TargetMachine *Machine = nullptr;
@@ -456,7 +456,7 @@
   if (OptLevelO1 || OptLevelO2 || OptLevelOs || OptLevelOz || OptLevelO3) {
     FPasses.reset(new FunctionPassManager(M.get()));
     if (DL)
-      FPasses->add(new DataLayoutPass(M.get()));
+      FPasses->add(new DataLayoutPass());
     if (TM.get())
       TM->addAnalysisPasses(*FPasses);