Applied following patches from Robert Collins and make sure IN_LIBXML is

* libxml.h: Applied following patches from Robert Collins
  and make sure IN_LIBXML is defined when compiling it
-------
* include/libxml/xmlversion.h.in (LIBXML_DLL_IMPORT): Use on Cygwin
  as well as Visual C.
* parser.c (XML_DIR_SEP): Don't use '\\' for Cygwin.
* parserInternals.c (XML_DIR_SEP): Don't use '\\' for Cygwin.
* strio.c (PLATFORM_UNIX): Define for Cygwin.
* triodef.h (TRIO_PLATFORM_UNIX): Define for Cygwin.
* xmlIO.c (xmlFileOpen): Use unix behaviour for Cygwin.
  Use binary mode opens for Cygwin (xmlFileOpenW xmlParserGetDirectory
  xmlSysIDExists xmlNoNetExists).
* xmllint.c: Don't include winsock2.h for Cygwin.
Daniel
diff --git a/parserInternals.c b/parserInternals.c
index f7ca646..9a570c9 100644
--- a/parserInternals.c
+++ b/parserInternals.c
@@ -9,7 +9,7 @@
 
 #include "libxml.h"
 
-#ifdef WIN32
+#if defined(WIN32) && !defined (__CYGWIN__)
 #define XML_DIR_SEP '\\'
 #else
 #define XML_DIR_SEP '/'