Revert "Give internal classes hidden visibility."

It works with clang, but GCC has different rules so we can't make all of those
hidden. This reverts commit r190534.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190536 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h b/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
index a08706a..4af7172 100644
--- a/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
+++ b/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
@@ -27,7 +27,7 @@
 /// SDDbgValue - Holds the information from a dbg_value node through SDISel.
 /// We do not use SDValue here to avoid including its header.
 
-class LLVM_LIBRARY_VISIBILITY SDDbgValue {
+class SDDbgValue {
 public:
   enum DbgValueKind {
     SDNODE = 0,             // value is the result of an expression