[NFC} fix "Target does not support MC emission!" Error in HowToUseJit Example.

[xgupta]

Summary

On running the HowToUseJIT example, after constructing the LLVM module it didn't get JIT compilation instead print the following error message:- Running foo: LLVM ERROR: Target does not support MC emission!
[1] 20154 abort (core dumped) HowToUseJIT.
So this patch fixes the issue and results as expected print 11.

[xgupta]

@lhames Please review the revision and if it looks fine, commit on my behalf as I don't have commit access.

[lhames]

LGTM. Thanks Shivam!

llvm/examples/HowToUseJIT/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   Core
   ExecutionEngine
   Interpreter
+  MC
+  MCJIT
   Support
   nativecodegen
   )
 
 add_llvm_example(HowToUseJIT
   HowToUseJIT.cpp
   )

llvm/examples/HowToUseJIT/HowToUseJIT.cpp

 //   conflict of temporary function name with some real
 //   existing function name?
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ExecutionEngine/ExecutionEngine.h"
 #include "llvm/ExecutionEngine/GenericValue.h"
+#include "llvm/ExecutionEngine/MCJIT.h"
 #include "llvm/IR/Argument.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
 #include <memory>
 #include <vector>
 
 using namespace llvm;
 
 int main() {
   InitializeNativeTarget();
+  LLVMInitializeNativeAsmPrinter();
 
   LLVMContext Context;
   
   // Create some module to put our function into it.
   std::unique_ptr<Module> Owner = std::make_unique<Module>("test", Context);
   Module *M = Owner.get();
 
   // Create the add1 function entry and insert this entry into module M.  The