Adding .clang-tidy readability-braces-around-statements option.

clang-tidy automatic changes. NO manual changes.

tests/test_virtual_functions.cpp

@@ -112,8 +112,9 @@ public:
     void operator=(const NonCopyable &) = delete;
     void operator=(NonCopyable &&) = delete;
     std::string get_value() const {
-        if (value)
+        if (value) {
             return std::to_string(*value);
+        }
         return "(null)";
     }
     ~NonCopyable() { print_destroyed(this); }