[Sanitizer] fix CMake build

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@159988 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/sanitizer_common/CMakeLists.txt b/lib/sanitizer_common/CMakeLists.txt
index a329d82..d797a56 100644
--- a/lib/sanitizer_common/CMakeLists.txt
+++ b/lib/sanitizer_common/CMakeLists.txt
@@ -4,6 +4,7 @@
 set(SANITIZER_SOURCES
   sanitizer_allocator.cc
   sanitizer_common.cc
+  sanitizer_flags.cc
   sanitizer_libc.cc
   sanitizer_linux.cc
   sanitizer_mac.cc