applied Serguei Narojnyi's patch to add native thread support on the Win32

* threads.c: applied Serguei Narojnyi's patch to add native
  thread support on the Win32 platform
* testThreadsWin32.c Makefile.am: added the test program also
  from Serguei, Win32 specific
* include/win32config.h include/libxml/xmlwin32version.h.in:
  added patch from Igor for the Windows thread specific defines.
Daniel
diff --git a/Makefile.am b/Makefile.am
index 6f06df1..6314acc 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -569,7 +569,8 @@
              example/Makefile.am example/gjobread.c example/gjobs.xml \
 	     $(man_MANS) libxml-2.0.pc.in \
 	     trionan.c trionan.h strio.c strio.h trio.c trio.h \
-	     triop.h triodef.h libxml.h
+	     triop.h triodef.h libxml.h \
+	     testThreadsWin32.c
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libxml-2.0.pc