patch 8.1.1848: 'langmap' is not used for CTRL-W command in terminal

Problem:    'langmap' is not used for CTRL-W command in terminal.
Solution:   Push the command in the typeahead buffer instead of the stuff
            buffer. (closes #4814)
diff --git a/src/terminal.c b/src/terminal.c
index 51e242f..95347a1 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -2372,8 +2372,13 @@
 	    }
 	    else if (termwinkey == 0 || c != termwinkey)
 	    {
-		stuffcharReadbuff(Ctrl_W);
-		stuffcharReadbuff(c);
+		char_u buf[MB_MAXBYTES + 2];
+
+		// Put the command into the typeahead buffer, when using the
+		// stuff buffer KeyStuffed is set and 'langmap' won't be used.
+		buf[0] = Ctrl_W;
+		buf[(*mb_char2bytes)(c, buf + 1) + 1] = NUL;
+		ins_typebuf(buf, REMAP_NONE, 0, TRUE, FALSE);
 		ret = OK;
 		goto theend;
 	    }
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 5496b63..e173b42 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -1686,6 +1686,13 @@
   call feedkeys("\<C-W>w", 'tx')
   call assert_equal(termwin, win_getid())
 
+  set langmap=xjyk
+  call feedkeys("\<C-L>x", 'tx')
+  call assert_equal(thiswin, win_getid())
+  call feedkeys("\<C-W>y", 'tx')
+  call assert_equal(termwin, win_getid())
+  set langmap=
+
   call feedkeys("\<C-L>gt", "xt")
   call assert_equal(3, tabpagenr())
   tabprev
diff --git a/src/version.c b/src/version.c
index b8a84ac..3ec385c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1848,
+/**/
     1847,
 /**/
     1846,