Fix recently introduced use-after-free error reported in <rdar://problem/7387478>.

llvm-svn: 87072
diff --git a/clang/lib/Frontend/PlistDiagnostics.cpp b/clang/lib/Frontend/PlistDiagnostics.cpp
index 1be9ea8..8a12b53 100644
--- a/clang/lib/Frontend/PlistDiagnostics.cpp
+++ b/clang/lib/Frontend/PlistDiagnostics.cpp
@@ -423,4 +423,6 @@
   
   if (FilesMade)
     FilesMade->push_back(OutputFile);
+  
+  BatchedDiags.clear();
 }