Mark StringView and StringViewLiteral as final.

src/String/StringView.hpp

@@ -42,7 +42,7 @@ static uint32_t constexpr Hash(char const* input) {
 static int constexpr CalcLength(const char* str) { return *str ? 1 + CalcLength(str + 1) : 0; }
 
 namespace ArbUt {
-    class StringView : public BasicStringView {
+    class StringView final : public BasicStringView {
     private:
         static __ConstStringCharHolder* __emptyString;
         static inline __ConstStringCharHolder* GetEmptyString() { return __emptyString; }

src/String/StringViewLiteral.hpp

@@ -6,7 +6,7 @@
 #include "StringView.hpp"
 
 namespace ArbUt {
-    class StringViewLiteral : public BasicStringView {
+    class StringViewLiteral final : public BasicStringView {
     private:
         const char* _str;