Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>

This is to be consistent with StringSet and ultimately with the standard
library's associative container insert function.

This lead to updating SmallSet::insert to return pair<iterator, bool>,
and then to update SmallPtrSet::insert to return pair<iterator, bool>,
and then to update all the existing users of those functions...

llvm-svn: 222334

llvm/lib/Analysis/CodeMetrics.cpp

@@ -40,7 +40,7 @@ static void completeEphemeralValues(SmallVector<const Value *, 16> &WorkSet,
     const Value *V = WorkSet.front();
     WorkSet.erase(WorkSet.begin());
 
-    if (!Visited.insert(V))
+    if (!Visited.insert(V).second)
       continue;
 
     // If all uses of this value are ephemeral, then so is this value.