patch 8.0.0222: blockwise put on multi-byte character misplaced

Problem:    When a multi-byte character ends in a zero byte, putting blockwise
            text puts it before the character instead of after it.
Solution:   Use int instead of char for the character under the cursor.
            (Luchr, closes #1403)  Add a test.

src/Makefile

@@ -2150,6 +2150,7 @@ test_arglist \
 	test_perl \
 	test_popup \
 	test_profile \
+	test_put \
 	test_quickfix \
 	test_regexp_latin \
 	test_regexp_utf8 \

src/ops.c

@@ -3550,7 +3550,7 @@ do_put(
      */
     if (y_type == MBLOCK)
     {
-	char	c = gchar_cursor();
+	int	c = gchar_cursor();
 	colnr_T	endcol2 = 0;
 
 	if (dir == FORWARD && c != NUL)

src/testdir/test_alot.vim

@@ -31,6 +31,7 @@ source test_mapping.vim
 source test_messages.vim
 source test_partial.vim
 source test_popup.vim
+source test_put.vim
 source test_reltime.vim
 source test_searchpos.vim
 source test_set.vim

src/testdir/test_put.vim

@@ -0,0 +1,12 @@
+
+func Test_put_block()
+  if !has('multi_byte')
+    return
+  endif
+  new
+  call feedkeys("i\<C-V>u2500\<CR>x\<ESC>", 'x')
+  call feedkeys("\<C-V>y", 'x')
+  call feedkeys("gg0p", 'x')
+  call assert_equal("\u2500x", getline(1))
+  bwipe!
+endfunc

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    222,
 /**/
     221,
 /**/