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...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222334 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/Inliner.cpp

@@ -219,7 +219,7 @@ static bool InlineCallIfPossible(CallSite CS, InlineFunctionInfo &IFI,
       
       // If the inlined function already uses this alloca then we can't reuse
       // it.
-      if (!UsedAllocas.insert(AvailableAlloca))
+      if (!UsedAllocas.insert(AvailableAlloca).second)
         continue;
       
       // Otherwise, we *can* reuse it, RAUW AI into AvailableAlloca and declare