[ORC] Fix the LLJITWithObjectCache example to address changes in ce2207ab.

void runJITWithCache(ObjectCache &ObjCache) {

  // Create an LLJIT instance with a custom CompileFunction.

  // Create an LLJIT instance with a custom IRCompiler.

  auto J = ExitOnErr(

      LLJITBuilder()

          .setCompileFunctionCreator(

              [&](JITTargetMachineBuilder JTMB)

                  -> Expected<IRCompileLayer::CompileFunction> {

                  -> Expected<std::unique_ptr<IRCompileLayer::IRCompiler>> {

                auto TM = JTMB.createTargetMachine();

                if (!TM)

                  return TM.takeError();

                return IRCompileLayer::CompileFunction(

                    TMOwningSimpleCompiler(std::move(*TM), &ObjCache));

                return std::make_unique<TMOwningSimpleCompiler>(std::move(*TM),

                                                                &ObjCache);

              })

          .create());