ADT/SparseSet.h: Fix up header dependencies.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151114 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/ADT/SparseSet.h b/include/llvm/ADT/SparseSet.h
index eba5cc0..b9928b9 100644
--- a/include/llvm/ADT/SparseSet.h
+++ b/include/llvm/ADT/SparseSet.h
@@ -21,6 +21,8 @@
 #define LLVM_ADT_SPARSESET_H
 
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/DataTypes.h"
+#include <limits>
 
 namespace llvm {