add version printing

#include "llvm/Support/FileSystem.h"

#include "llvm/Support/SourceMgr.h"

#include "llvm/Support/raw_ostream.h"

#include "llvm/Support/ToolOutputFile.h"

#include "llvm/Support/VersionTuple.h"

#include "llvm/Support/ManagedStatic.h"

using namespace llvm;

cl::OptionCategory ReverserCategory("Reverser Options");

static void printReverserVersion(llvm::raw_ostream& out) {

  out << "reverser version 1.0.3\n";

  out << "  using LLVM " << LLVM_VERSION_STRING << "\n";

}

enum ReturnValue { OK, CANNOT_REVERSE, CANNOT_OPEN_INPUT, CANNOT_OPEN_OUTPUT };

int main(int argc, char** argv)

{

    LLVMContext context;

    cl::SetVersionPrinter(printReverserVersion);

    // CLI options

    cl::opt<std::string> inputFilename(cl::Positional, cl::desc("<input file>"), cl::Required,

                                       cl::cat(ReverserCategory));