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/SplitKit.h b/lib/CodeGen/SplitKit.h
index e0a9c31..f029c73 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -39,7 +39,7 @@
 
 /// SplitAnalysis - Analyze a LiveInterval, looking for live range splitting
 /// opportunities.
-class LLVM_LIBRARY_VISIBILITY SplitAnalysis {
+class SplitAnalysis {
 public:
   const MachineFunction &MF;
   const VirtRegMap &VRM;
@@ -208,7 +208,7 @@
 /// - Finish the current interval with closeIntv and repeat from 2.
 /// - Rewrite instructions with finish().
 ///
-class LLVM_LIBRARY_VISIBILITY SplitEditor {
+class SplitEditor {
   SplitAnalysis &SA;
   LiveIntervals &LIS;
   VirtRegMap &VRM;