patch 8.1.1401: misspelled mkspellmem as makespellmem

Problem:    Misspelled mkspellmem as makespellmem.
Solution:   Drop duplicate help entry, fix test. (Naruhiko Nishino, Ken
            Takata, closes #4437)

runtime/doc/options.txt

@@ -4913,12 +4913,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 <	This option cannot be set from a |modeline| or in the |sandbox|, for
 	security reasons.
 
-						*'makespellmem'* *'msm'*
-'makespellmem' 'msm'		string	(default "460000,2000,500")
-			global
-	Values relevant only when compressing a spell file, see |spell|.
-	This option cannot be set from a |modeline| or in the |sandbox|.
-
 						*'matchpairs'* *'mps'*
 'matchpairs' 'mps'	string	(default "(:),{:},[:]")
 			local to buffer
@@ -5070,6 +5064,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 <	If you have less than 512 Mbyte |:mkspell| may fail for some
 	languages, no matter what you set 'mkspellmem' to.
 
+	This option cannot be set from a |modeline| or in the |sandbox|.
+
 				   *'modeline'* *'ml'* *'nomodeline'* *'noml'*
 'modeline' 'ml'		boolean	(Vim default: on (off for root),
 				 Vi default: off)

src/testdir/test_modeline.vim

@@ -116,7 +116,7 @@ func Test_modeline_fails_always()
   call s:modeline_fails('luadll', 'luadll=Something()', 'E520:')
   call s:modeline_fails('makeef', 'makeef=Something()', 'E520:')
   call s:modeline_fails('makeprg', 'makeprg=Something()', 'E520:')
-  call s:modeline_fails('makespellmem', 'makespellmem=Something()', 'E520:')
+  call s:modeline_fails('mkspellmem', 'mkspellmem=Something()', 'E520:')
   call s:modeline_fails('mzschemedll', 'mzschemedll=Something()', 'E520:')
   call s:modeline_fails('mzschemegcdll', 'mzschemegcdll=Something()', 'E520:')
   call s:modeline_fails('modelineexpr', 'modelineexpr', 'E520:')

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1401,
 /**/
     1400,
 /**/