Give internal classes hidden visibility.

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190534 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Bitcode/Writer/ValueEnumerator.h b/lib/Bitcode/Writer/ValueEnumerator.h
index d1ca15f..f208eb3 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.h
+++ b/lib/Bitcode/Writer/ValueEnumerator.h
@@ -34,7 +34,7 @@
 class MDSymbolTable;
 class raw_ostream;
 
-class ValueEnumerator {
+class LLVM_LIBRARY_VISIBILITY ValueEnumerator {
 public:
   typedef std::vector<Type*> TypeList;