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/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index ec640bc..6463eca 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -79,7 +79,7 @@
 /// SelectionDAGBuilder - This is the common target-independent lowering
 /// implementation that is parameterized by a TargetLowering object.
 ///
-class LLVM_LIBRARY_VISIBILITY SelectionDAGBuilder {
+class SelectionDAGBuilder {
   /// CurInst - The current instruction being visited
   const Instruction *CurInst;