Update to 7-Zip 17.01 Beta from Igor Pavlov

- Minor speed optimization for LZMA2 (xz and 7z) multi-threading compression.
  7-Zip now uses additional memory buffers for multi-block LZMA2 compression.
  CPU utilization was slightly improved.
- 7-zip now creates multi-block xz archives by default. Block size can be
  specified with -ms[Size]{m|g} switch.
- xz decoder now can unpack random block from multi-block xz archives.  7-Zip
  File Manager now can open nested multi-block xz archives (for example,
  image.iso.xz) without full unpacking of xz archive.
- 7-Zip now can create zip archives from stdin to stdout.
- 7-Zip command line: @listfile now doesn't work after -- switch.  Use
  -i@listfile before -- switch instead.

fixed bugs:
- 7-Zip could add unrequired alternate file streams to WIM archives, for
  commands that contain filename wildcards and -sns switch.
- 7-Zip 17.00 beta crashed for commands that write anti-item to 7z archive.
- 7-Zip 17.00 beta ignored "Use large memory pages" option.

CPP/7zip/UI/Common/DirItem.h

@@ -21,7 +21,7 @@ struct CDirItemsStat
   
   UInt64 NumErrors;
   
-  UInt64 Get_NumItems() const { return NumDirs + NumFiles + NumAltStreams; }
+  // UInt64 Get_NumItems() const { return NumDirs + NumFiles + NumAltStreams; }
   UInt64 Get_NumDataItems() const { return NumFiles + NumAltStreams; }
   UInt64 GetTotalBytes() const { return FilesSize + AltStreamsSize; }
 
@@ -43,6 +43,30 @@ struct CDirItemsStat
     {}
 };
 
+
+struct CDirItemsStat2: public CDirItemsStat
+{
+  UInt64 Anti_NumDirs;
+  UInt64 Anti_NumFiles;
+  UInt64 Anti_NumAltStreams;
+  
+  // UInt64 Get_NumItems() const { return Anti_NumDirs + Anti_NumFiles + Anti_NumAltStreams + CDirItemsStat::Get_NumItems(); }
+  UInt64 Get_NumDataItems2() const { return Anti_NumFiles + Anti_NumAltStreams + CDirItemsStat::Get_NumDataItems(); }
+
+  bool IsEmpty() const { return CDirItemsStat::IsEmpty()
+        && 0 == Anti_NumDirs
+        && 0 == Anti_NumFiles
+        && 0 == Anti_NumAltStreams; }
+  
+  CDirItemsStat2():
+      Anti_NumDirs(0),
+      Anti_NumFiles(0),
+      Anti_NumAltStreams(0)
+    {}
+};
+
+
+
 #define INTERFACE_IDirItemsCallback(x) \
   virtual HRESULT ScanError(const FString &path, DWORD systemError) x; \
   virtual HRESULT ScanProgress(const CDirItemsStat &st, const FString &path, bool isDir) x; \