Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid needing to mention the size.

llvm-svn: 216158
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 4cc1e96..b72d850 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -283,7 +283,7 @@
 }
 
 static bool canTrapImpl(const Constant *C,
-                        SmallPtrSet<const ConstantExpr *, 4> &NonTrappingOps) {
+                        SmallPtrSetImpl<const ConstantExpr *> &NonTrappingOps) {
   assert(C->getType()->isFirstClassType() && "Cannot evaluate aggregate vals!");
   // The only thing that could possibly trap are constant exprs.
   const ConstantExpr *CE = dyn_cast<ConstantExpr>(C);