[ADT/STLExtras.h] - Add llvm::is_sorted wrapper and update callers.

It can be used to avoid passing the begin and end of a range.
This makes the code shorter and it is consistent with another
wrappers we already have.

Differential revision: https://reviews.llvm.org/D78016

llvm/lib/Bitcode/Writer/ValueEnumerator.cpp

@@ -231,9 +231,9 @@ static void predictValueUseListOrderImpl(const Value *V, const Function *F,
     return LU->getOperandNo() > RU->getOperandNo();
   });
 
-  if (std::is_sorted(
-          List.begin(), List.end(),
-          [](const Entry &L, const Entry &R) { return L.second < R.second; }))
+  if (llvm::is_sorted(List, [](const Entry &L, const Entry &R) {
+        return L.second < R.second;
+      }))
     // Order is already correct.
     return;