AK: Add nodiscard attribute to BinarySearch functions

Author: https://github.com/ldm5180
Commit: 84d9e537cd
Pull-request: https://github.com/SerenityOS/serenity/pull/14395
Reviewed-by: https://github.com/linusg

AK/BinarySearch.h

@@ -13,7 +13,7 @@ namespace AK {
 
 struct DefaultComparator {
     template<typename T, typename S>
-    constexpr int operator()(T& lhs, S& rhs)
+    [[nodiscard]] constexpr int operator()(T& lhs, S& rhs)
     {
         if (lhs > rhs)
             return 1;