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