[ADT] Teach set_intersect to erase with iterators (#99569)

Without this patch, we erase an element in S1 by value even though we
have an interator pointing to it.  This patch tries to use erase(iter)
to avoid redundant lookups.

Author: kazutakahirata

llvm/include/llvm/ADT/SetOperations.h

@@ -60,11 +60,11 @@ template <class S1Ty, class S2Ty> void set_intersect(S1Ty &S1, const S2Ty &S2) {
   if constexpr (detail::HasMemberRemoveIf<S1Ty, decltype(Pred)>) {
     S1.remove_if(Pred);
   } else {
-    for (typename S1Ty::iterator I = S1.begin(); I != S1.end();) {
-      const auto &E = *I;
-      ++I;
-      if (!S2.count(E))
-        S1.erase(E); // Erase element if not in S2
+    typename S1Ty::iterator Next;
+    for (typename S1Ty::iterator I = S1.begin(); I != S1.end(); I = Next) {
+      Next = std::next(I);
+      if (!S2.count(*I))
+        S1.erase(I); // Erase element if not in S2
     }
   }
 }