Reintroduce the serialization library, with fixed dependencies.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111279 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index bc2cd46..8ecfcbe 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -8,6 +8,7 @@
 add_subdirectory(Analysis)
 add_subdirectory(Rewrite)
 add_subdirectory(Driver)
+add_subdirectory(Serialization)
 add_subdirectory(Frontend)
 add_subdirectory(Index)
 add_subdirectory(Checker)