Give helper classes/functions local linkage. NFC.

llvm-svn: 351016
diff --git a/llvm/lib/Transforms/IPO/HotColdSplitting.cpp b/llvm/lib/Transforms/IPO/HotColdSplitting.cpp
index 5d989a4..924a7d5 100644
--- a/llvm/lib/Transforms/IPO/HotColdSplitting.cpp
+++ b/llvm/lib/Transforms/IPO/HotColdSplitting.cpp
@@ -295,6 +295,7 @@
 /// A pair of (basic block, score).
 using BlockTy = std::pair<BasicBlock *, unsigned>;
 
+namespace {
 /// A maximal outlining region. This contains all blocks post-dominated by a
 /// sink block, the sink block itself, and all blocks dominated by the sink.
 class OutliningRegion {
@@ -458,6 +459,7 @@
     return SubRegion;
   }
 };
+} // namespace
 
 bool HotColdSplitting::outlineColdRegions(Function &F, ProfileSummaryInfo &PSI,
                                           BlockFrequencyInfo *BFI,