Several Windows related cleanups:
* Removed a #define from pyconfig.h. The macro was already defined a few lines higher.
* Fixed path to tix in the build_tkinter.py script
* Changed make_buildinfo.c to use versions of unlink and strcat which are considered safe by Windows (as suggested by MvL).
* Removed two defines from pyproject.vsprops that are no longer required. Both are defined in pyconfig.h and make_buildinfo.c doesn't use the unsafe versions any more (as suggested by MvL).
* Added some more information about PGO and the property files to PCbuild9/readme.txt.

Are you fine with the changes, Martin?
diff --git a/PCbuild9/readme.txt b/PCbuild9/readme.txt
index fd3967a..ef3b97d 100644
--- a/PCbuild9/readme.txt
+++ b/PCbuild9/readme.txt
@@ -281,6 +281,14 @@
 Profile Guided Optimization
 ---------------------------
 
+The solution has two configurations for PGO. The PGInstrument configuration
+must be build first. The PGInstrument binaries are lniked against a profiling
+library and contain extra debug information. The PGUpdate configuration takes the profiling data and generates optimized binaries.
+
+The build_pgo.bat script automates the creation of optimized binaries. It
+creates the PGI files, runs the unit test suite or PyBench with the PGI
+python and finally creates the optimized files.
+
 http://msdn2.microsoft.com/en-us/library/e7k32f4k(VS.90).aspx
 
 Static library
@@ -300,7 +308,7 @@
 (*.vsprops). The properties can be viewed and altered in the Property
 Manager (View -> Other Windows -> Property Manager).
 
- * debug (debug macros)
+ * debug (debug macro: _DEBUG)
  * pginstrument (PGO)
  * pgupdate (PGO)
     +-- pginstrument
@@ -310,8 +318,8 @@
  * pyd_d (python extension, debug build)
     +-- debug
     +-- pyproject
- * pyproject (base settings for all projects)
- * release (release macros)
+ * pyproject (base settings for all projects, user macros like PyDllName)
+ * release (release macro: NDEBUG)
  * x64 (AMD64 / x64 platform specific settings)
 
 The pyproject propertyfile defines _WIN32 and x64 defines _WIN64 and _M_X64
@@ -320,6 +328,7 @@
 
 YOUR OWN EXTENSION DLLs
 -----------------------
+
 If you want to create your own extension module DLL, there's an example
 with easy-to-follow instructions in ../PC/example/; read the file
 readme.txt there first.