[CodeGenPrepare] Move CodeGenPrepare into lib/CodeGen.

CodeGenPrepare uses extensively TargetLowering which is part of libLLVMCodeGen.
This is a layer violation which would introduce eventually a dependence on
CodeGen in ScalarOpts.

Move CodeGenPrepare into libLLVMCodeGen to avoid that.

Follow-up of <rdar://problem/15519855>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201912 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/CMakeLists.txt

@@ -1,6 +1,5 @@
 add_llvm_library(LLVMScalarOpts
   ADCE.cpp
-  CodeGenPrepare.cpp
   ConstantHoisting.cpp
   ConstantProp.cpp
   CorrelatedValuePropagation.cpp

lib/Transforms/Scalar/Scalar.cpp

@@ -29,7 +29,6 @@ using namespace llvm;
 void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeADCEPass(Registry);
   initializeSampleProfileLoaderPass(Registry);
-  initializeCodeGenPreparePass(Registry);
   initializeConstantHoistingPass(Registry);
   initializeConstantPropagationPass(Registry);
   initializeCorrelatedValuePropagationPass(Registry);