Include xf86Cursor.h instead of xf86RamDac.h

ramdac drivers have been removed from xserver since version 21.0.99.1
and xorg/xserver@f0385fb4

 resulting in the following build failure:

In file included from ../../src/leo_accel.c:39:
../../src/leo.h:29:10: fatal error: xf86RamDac.h: No such file or directory
   29 | #include "xf86RamDac.h"
      |          ^~~~~~~~~~~~~~

but xf86RamDac.h in turn included xf86Cursor.h which we still need.
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

src/leo.h

@@ -26,7 +26,7 @@
 
 #include "xf86.h"
 #include "xf86_OSproc.h"
-#include "xf86RamDac.h"
+#include "xf86Cursor.h"
 #include <X11/Xmd.h>
 #include "gcstruct.h"
 #include "leo_regs.h"