patch 8.1.1271: compiler warnings for use of STRNCPY()

Problem:    Compiler warnings for use of STRNCPY(). (John Marriott)
Solution:   Use mch_memmove() instead of STRNCPY().

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1271,
 /**/
     1270,
 /**/