Fix CMake configuration (forgot to add a file in the last commit).

llvm-svn: 217297
diff --git a/lldb/source/API/CMakeLists.txt b/lldb/source/API/CMakeLists.txt
index d58096d..7e9dd2d 100644
--- a/lldb/source/API/CMakeLists.txt
+++ b/lldb/source/API/CMakeLists.txt
@@ -43,6 +43,7 @@
   SBSymbolContextList.cpp
   SBTarget.cpp
   SBThread.cpp
+  SBThreadCollection.cpp
   SBType.cpp
   SBTypeCategory.cpp
   SBTypeEnumMember.cpp