Rename to addPPCallbacks since we're effectively adding a callback and maybe chaining it to an existing one

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97913 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/DependencyFile.cpp b/lib/Frontend/DependencyFile.cpp
index 9487b1a..de2b056 100644
--- a/lib/Frontend/DependencyFile.cpp
+++ b/lib/Frontend/DependencyFile.cpp
@@ -74,7 +74,7 @@
     return;
   }
 
-  PP.setPPCallbacks(new DependencyFileCallback(&PP, OS, Opts));
+  PP.addPPCallbacks(new DependencyFileCallback(&PP, OS, Opts));
 }
 
 /// FileMatchesDepCriteria - Determine whether the given Filename should be