Don't depend on PathV1.h including set.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184310 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/InheritViz.cpp

@@ -21,6 +21,7 @@
 #include "llvm/Support/PathV1.h"
 #include "llvm/Support/raw_ostream.h"
 #include <map>
+#include <set>
 
 using namespace llvm;