Add a missing build dependency.

Patch by Chen-Pang He.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@320754 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Common/CMakeLists.txt b/Common/CMakeLists.txt
index 2d78383..b376893 100644
--- a/Common/CMakeLists.txt
+++ b/Common/CMakeLists.txt
@@ -17,6 +17,7 @@
 
   LINK_COMPONENTS
   Codegen
+  Core
   Demangle
   MC
   Option