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.

llvm-svn: 190536
diff --git a/llvm/lib/CodeGen/CriticalAntiDepBreaker.h b/llvm/lib/CodeGen/CriticalAntiDepBreaker.h
index ef4059e..565d20b 100644
--- a/llvm/lib/CodeGen/CriticalAntiDepBreaker.h
+++ b/llvm/lib/CodeGen/CriticalAntiDepBreaker.h
@@ -31,7 +31,7 @@
 class TargetInstrInfo;
 class TargetRegisterInfo;
 
-  class LLVM_LIBRARY_VISIBILITY CriticalAntiDepBreaker : public AntiDepBreaker {
+  class CriticalAntiDepBreaker : public AntiDepBreaker {
     MachineFunction& MF;
     MachineRegisterInfo &MRI;
     const TargetInstrInfo *TII;