Revert "Temporary hack to make the new version of expat build under windows"

A proper fix has been provided

This reverts commit 655971208f.

simgear/xml/xmlparse.c

@@ -22,11 +22,6 @@
 #include "expat_config.h"
 #endif /* ndef COMPILED_FROM_DSP */
 
-// FIXME: I just want to compile
-#ifdef _MSC_VER
-#define HAVE_MEMMOVE 1
-#endif
-
 #include "ascii.h"
 #include "expat.h"