Add an operator< for SmallVector.

llvm-svn: 51791

include/llvm/ADT/SmallVector.h

@@ -308,6 +308,11 @@ public:
   }
   bool operator!=(const SmallVectorImpl &RHS) const { return !(*this == RHS); }
 
+  bool operator<(const SmallVectorImpl &RHS) const {
+    return std::lexicographical_compare(begin(), end(),
+                                        RHS.begin(), RHS.end());
+  }
+  
 private:
   /// isSmall - Return true if this is a smallvector which has not had dynamic
   /// memory allocated for it.