patch 8.2.4401: map listing does not clear the rest of the command line

Problem:    Map listing does not clear the rest of the command line.
Solution:   Call msg_clear_eos(). (closes #5623, closes #5962)

src/map.c

@@ -204,6 +204,7 @@ showmap(
     if (p_verbose > 0)
 	last_set_msg(mp->m_script_ctx);
 #endif
+    msg_clr_eos();
     out_flush();			// show one line at a time
 }
 

src/testdir/dumps/Test_map_list_1.dump

@@ -0,0 +1,6 @@
+> +0&#ffffff0@74
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|n+0#0000000&| @1|a| @12|b| @38|0|,|0|-|1| @8|A|l@1| 

src/testdir/test_mapping.vim

@@ -540,7 +540,6 @@ func Test_expr_map_restore_cursor()
   END
   call writefile(lines, 'XtestExprMap')
   let buf = RunVimInTerminal('-S XtestExprMap', #{rows: 10})
-  call TermWait(buf)
   call term_sendkeys(buf, "\<C-B>")
   call VerifyScreenDump(buf, 'Test_map_expr_1', {})
 
@@ -549,6 +548,22 @@ func Test_expr_map_restore_cursor()
   call delete('XtestExprMap')
 endfunc
 
+func Test_map_listing()
+  CheckScreendump
+
+  let lines =<< trim END
+      nmap a b
+  END
+  call writefile(lines, 'XtestMapList')
+  let buf = RunVimInTerminal('-S XtestMapList', #{rows: 6})
+  call term_sendkeys(buf, ":                      nmap a\<CR>")
+  call VerifyScreenDump(buf, 'Test_map_list_1', {})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('XtestMapList')
+endfunc
+
 func Test_expr_map_error()
   CheckScreendump
 
@@ -565,7 +580,6 @@ func Test_expr_map_error()
   END
   call writefile(lines, 'XtestExprMap')
   let buf = RunVimInTerminal('-S XtestExprMap', #{rows: 10})
-  call TermWait(buf)
   call term_sendkeys(buf, "\<F2>")
   call TermWait(buf)
   call term_sendkeys(buf, "\<CR>")

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4401,
 /**/
     4400,
 /**/