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.

C/Util/7zipInstall/7zipInstall.c

@@ -1,5 +1,5 @@
 /* 7zipInstall.c - 7-Zip Installer
-2017-04-04 : Igor Pavlov : Public domain */
+2017-08-28 : Igor Pavlov : Public domain */
 
 #include "Precomp.h"
 
@@ -154,7 +154,7 @@ static WRes MyCreateDir(LPCWSTR name)
 }
 
 #define IS_SEPAR(c) (c == WCHAR_PATH_SEPARATOR)
-#define IS_LETTER_CHAR(c) ((c) >= 'a' && (c) <= 'z' || (c) >= 'A' && (c) <= 'Z')
+#define IS_LETTER_CHAR(c) (((c) >= 'a' && (c) <= 'z') || ((c) >= 'A' && (c) <= 'Z'))
 #define IS_DRIVE_PATH(s) (IS_LETTER_CHAR(s[0]) && s[1] == ':' && IS_SEPAR(s[2]))
 
 static int ReverseFind_PathSepar(const wchar_t *s)