patch 8.0.0241: fallback implementation of mch_memmove is unused

Problem:    Vim defines a mch_memmove() function but it doesn't work, thus is
            always unused.
Solution:   Remove the mch_memmove implementation. (suggested by Dominique
            Pelle)
diff --git a/src/version.c b/src/version.c
index 4e41617..08b5dec 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    241,
+/**/
     240,
 /**/
     239,