xdiff: remove duplicate headers from xpatience.c

92b7de93fb (Implement the patience diff algorithm, 2009-01-07) added them
but were already part of xinclude.h

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

xdiff/xpatience.c

@@ -20,8 +20,6 @@
  *
  */
 #include "xinclude.h"
-#include "xtypes.h"
-#include "xdiff.h"
 
 /*
  * The basic idea of patience diff is to find lines that are unique in