[ADT] Simplify llvm::sort with constexpr if (NFC)

[dblaikie]

Awesome!

llvm/include/llvm/ADT/STLExtras.h

 // is trivially copyable.
 using sort_trivially_copyable = std::conjunction<
     std::is_pointer<T>,
     std::is_trivially_copyable<typename std::iterator_traits<T>::value_type>>;
 } // namespace detail
 
 // Provide wrappers to std::sort which shuffle the elements before sorting
 // to help uncover non-deterministic behavior (PR35135).
-template <typename IteratorTy,
-          std::enable_if_t<!detail::sort_trivially_copyable<IteratorTy>::value,
-                           int> = 0>
+template <typename IteratorTy>
 inline void sort(IteratorTy Start, IteratorTy End) {
+  if constexpr (detail::sort_trivially_copyable<IteratorTy>::value) {
+    // Forward trivially copyable types to array_pod_sort. This avoids a large
+    // amount of code bloat for a minor performance hit.
+    array_pod_sort(Start, End);
+  } else {
 #ifdef EXPENSIVE_CHECKS
     detail::presortShuffle<IteratorTy>(Start, End);
 #endif
     std::sort(Start, End);
   }
-
-// Forward trivially copyable types to array_pod_sort. This avoids a large
-// amount of code bloat for a minor performance hit.
-template <typename IteratorTy,
-          std::enable_if_t<detail::sort_trivially_copyable<IteratorTy>::value,
-                           int> = 0>
-inline void sort(IteratorTy Start, IteratorTy End) {
-  array_pod_sort(Start, End);
 }
 
 template <typename Container> inline void sort(Container &&C) {
   llvm::sort(adl_begin(C), adl_end(C));
 }
 
 template <typename IteratorTy, typename Compare>
 inline void sort(IteratorTy Start, IteratorTy End, Compare Comp) {