[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 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);
 }