[libclang] Make sure Preprocessor is set in ASTUnit during indexing.

llvm-svn: 148319
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 5272636..e31bf55 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -262,6 +262,8 @@
   }    
 }
 
+void ASTUnit::setPreprocessor(Preprocessor *pp) { PP = pp; }
+
 /// \brief Determine the set of code-completion contexts in which this 
 /// declaration should be shown.
 static unsigned getDeclShowContexts(NamedDecl *ND,