showbc: Quote block name, so it was easily visible.

py/showbc.c

@@ -89,7 +89,7 @@ void mp_byte_code_print(const byte *ip, int len) {
     {
         qstr source_file = code_info[4] | (code_info[5] << 8) | (code_info[6] << 16) | (code_info[7] << 24);
         qstr block_name = code_info[8] | (code_info[9] << 8) | (code_info[10] << 16) | (code_info[11] << 24);
-        printf("File %s, block %s\n", qstr_str(source_file), qstr_str(block_name));
+        printf("File %s, block '%s'\n", qstr_str(source_file), qstr_str(block_name));
         machine_int_t bc = (code_info + code_info_size) - ip;
         machine_uint_t source_line = 1;
         printf("  bc=" INT_FMT " line=" UINT_FMT "\n", bc, source_line);