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
diff --git a/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp b/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
index 9ac62b0..d7ba6d4 100644
--- a/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
+++ b/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
@@ -455,7 +455,8 @@
 
 bool MemDefsUses::updateDefsUses(ValueType V, bool MayStore) {
   if (MayStore)
-    return !Defs.insert(V) || Uses.count(V) || SeenNoObjStore || SeenNoObjLoad;
+    return !Defs.insert(V).second || Uses.count(V) || SeenNoObjStore ||
+           SeenNoObjLoad;
 
   Uses.insert(V);
   return Defs.count(V) || SeenNoObjStore;