[mlir] Add a function to print C-strings to RunnerUtils.cpp.

[pifon2a]

update

[pifon2a]

Add an awesome test.

mlir/lib/ExecutionEngine/RunnerUtils.cpp

 extern "C" void _mlir_ciface_print_memref_f32(UnrankedMemRefType<float> *M) {
   impl::printMemRef(*M);
 }
 
 extern "C" void _mlir_ciface_print_memref_f64(UnrankedMemRefType<double> *M) {
   impl::printMemRef(*M);
 }
 
+extern "C" void _mlir_ciface_print_string(UnrankedMemRefType<int64_t> *M) {
+  impl::printMemRef(*M);
+}
+
 extern "C" int64_t _mlir_ciface_nano_time() {
   auto now = std::chrono::high_resolution_clock::now();
   auto duration = now.time_since_epoch();
   auto nanoseconds =
       std::chrono::duration_cast<std::chrono::nanoseconds>(duration);
   return nanoseconds.count();
 }
 
extern "C" void print_memref_f32(int64_t rank, void *ptr) {
   _mlir_ciface_print_memref_f32(&descriptor);
 }
 
 extern "C" void print_memref_f64(int64_t rank, void *ptr) {
   UnrankedMemRefType<double> descriptor = {rank, ptr};
   _mlir_ciface_print_memref_f64(&descriptor);
 }
 
+extern "C" void print_c_string(char *str) { printf("%s", str); }
+
 extern "C" void
 _mlir_ciface_print_memref_0d_f32(StridedMemRefType<float, 0> *M) {
   impl::printMemRef(*M);
 }
 extern "C" void
 _mlir_ciface_print_memref_1d_f32(StridedMemRefType<float, 1> *M) {
   impl::printMemRef(*M);
 }