io: Add reset of new bytecount infrastructure

Author: pcanal

io/io/inc/TBufferFile.h

@@ -120,6 +120,8 @@ class TBufferFile : public TBufferIO {
    const ByteCountFinder_t& GetByteCounts() const { return fByteCounts; }
    void SetByteCounts(ByteCountFinder_t &&byteCounts) { fByteCounts = std::move(byteCounts); }
 
+   void ResetMap() override;
+
    using TBufferIO::CheckObject;
 
    // basic types and arrays of basic types

io/io/src/TBufferFile.cxx

@@ -114,6 +114,16 @@ TBufferFile::~TBufferFile()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// Reset buffer maps and clear byte-count tracking structures.
+
+void TBufferFile::ResetMap()
+{
+   TBufferIO::ResetMap();
+   fByteCountStack.clear();
+   fByteCounts.clear();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// Increment level.