Update for LLVM API change.

llvm-svn: 220742
diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 0bd53b8..1eb59bd 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -154,7 +154,7 @@
       // Link LinkModule into this module if present, preserving its validity.
       if (LinkModule) {
         if (Linker::LinkModules(
-                M, LinkModule.get(), Linker::PreserveSource,
+                M, LinkModule.get(),
                 [=](const DiagnosticInfo &DI) { linkerDiagnosticHandler(DI); }))
           return;
       }