AK: Make C++ concepts support mandatory for compilers

The latest GCC and Clang versions both support this, so we can freely
use these in our code.

AK/Concepts.h

@@ -11,8 +11,6 @@
 
 namespace AK::Concepts {
 
-#if defined(__cpp_concepts) && !defined(__COVERITY__)
-
 template<typename T>
 concept Integral = IsIntegral<T>;
 
@@ -31,13 +29,15 @@ concept Unsigned = IsUnsigned<T>;
 template<typename T, typename U>
 concept SameAs = IsSame<T, U>;
 
+// FIXME: remove once Clang formats these properly.
+// clang-format off
 template<typename Func, typename... Args>
 concept VoidFunction = requires(Func func, Args... args)
 {
     {
         func(args...)
     }
-    ->SameAs<void>;
+    -> SameAs<void>;
 };
 
 template<typename Func, typename... Args>
@@ -46,15 +46,11 @@ concept IteratorFunction = requires(Func func, Args... args)
     {
         func(args...)
     }
-    ->SameAs<IterationDecision>;
+    -> SameAs<IterationDecision>;
 };
-
-#endif
-
+// clang-format on
 }
 
-#if defined(__cpp_concepts) && !defined(__COVERITY__)
-
 using AK::Concepts::Arithmetic;
 using AK::Concepts::FloatingPoint;
 using AK::Concepts::Integral;
@@ -62,5 +58,3 @@ using AK::Concepts::IteratorFunction;
 using AK::Concepts::Signed;
 using AK::Concepts::Unsigned;
 using AK::Concepts::VoidFunction;
-
-#endif

AK/Userspace.h

@@ -12,16 +12,10 @@
 
 namespace AK {
 
-// HACK: This is just here to make syntax highlighting work in Qt Creator.
-//       Once it supports C++20 concepts, we can remove this.
-#if defined(__cpp_concepts) && !defined(__COVERITY__)
 template<typename T>
 concept PointerTypeName = IsPointer<T>;
-template<PointerTypeName T>
-#else
-template<typename T, typename EnableIf<IsPointer<T>, int>::Type = 0>
-#endif
 
+template<PointerTypeName T>
 class Userspace {
 public:
     Userspace() = default;