Give internal classes hidden visibility.

Worth 100k on a linux/x86_64 Release+Asserts clang.

llvm-svn: 190534
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.h b/llvm/lib/CodeGen/LiveDebugVariables.h
index 58a3f0f..1d449fd 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.h
+++ b/llvm/lib/CodeGen/LiveDebugVariables.h
@@ -30,7 +30,7 @@
 class LiveIntervals;
 class VirtRegMap;
 
-class LiveDebugVariables : public MachineFunctionPass {
+class LLVM_LIBRARY_VISIBILITY LiveDebugVariables : public MachineFunctionPass {
   void *pImpl;
 public:
   static char ID; // Pass identification, replacement for typeid