Move PCHContainerOperations from Frontend to Serialization

Fix a layering violation.  Frontend depends on Serialization, so anything used
by both should be in Serialization.

llvm-svn: 348907
diff --git a/clang/lib/Serialization/CMakeLists.txt b/clang/lib/Serialization/CMakeLists.txt
index 95b33c3..a312cb9 100644
--- a/clang/lib/Serialization/CMakeLists.txt
+++ b/clang/lib/Serialization/CMakeLists.txt
@@ -17,6 +17,7 @@
   Module.cpp
   ModuleFileExtension.cpp
   ModuleManager.cpp
+  PCHContainerOperations.cpp
 
   ADDITIONAL_HEADERS
   ASTCommon.h