patch 8.0.0246: compiler warnings for int to pointer conversion

Problem:    Compiler warnings for int to pointer conversion.
Solution:   Fix macro for mch_memmove(). (John Marriott)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    246,
 /**/
     245,
 /**/

src/vim.h

@@ -1715,7 +1715,7 @@ typedef unsigned short disptick_T;	/* display tick type */
 typedef void	    *vim_acl_T;		/* dummy to pass an ACL to a function */
 
 #ifndef mch_memmove
-# define mch_memmove(to, from, len) memmove((char*)(to), (char*)(from), (char*)(len))
+# define mch_memmove(to, from, len) memmove((char*)(to), (char*)(from), (size_t)(len))
 #endif
 
 /*