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/ScheduleDAGSDNodes.h b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
index 60663c0..2ff37e0 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
@@ -33,7 +33,7 @@
   /// edges.  Physical register dependence information is not carried in
   /// the DAG and must be handled explicitly by schedulers.
   ///
-  class LLVM_LIBRARY_VISIBILITY ScheduleDAGSDNodes : public ScheduleDAG {
+  class ScheduleDAGSDNodes : public ScheduleDAG {
   public:
     MachineBasicBlock *BB;
     SelectionDAG *DAG;                    // DAG of the current basic block