Move classes defined in a cpp file into an anonymous namespace.

No functionality change intended.

llvm-svn: 259883
diff --git a/llvm/lib/ProfileData/CoverageMappingReader.cpp b/llvm/lib/ProfileData/CoverageMappingReader.cpp
index fa4d6d6..633de32 100644
--- a/llvm/lib/ProfileData/CoverageMappingReader.cpp
+++ b/llvm/lib/ProfileData/CoverageMappingReader.cpp
@@ -306,6 +306,7 @@
   return Data.substr(Pointer - Address, Size);
 }
 
+namespace {
 struct CovMapFuncRecordReader {
   // The interface to read coverage mapping function records for
   // a module. \p Buf is a reference to the buffer pointer pointing
@@ -413,6 +414,7 @@
     return std::error_code();
   }
 };
+} // end anonymous namespace
 
 template <class IntPtrT, support::endianness Endian>
 std::unique_ptr<CovMapFuncRecordReader> CovMapFuncRecordReader::get(