patch 8.0.1662: showing dump diff doesn't mention both file names

Problem:    Showing dump diff doesn't mention both file names.
Solution:   Add the file name in the separator line.

src/terminal.c

@@ -41,7 +41,7 @@
 * - Add a way to set the 16 ANSI colors, to be used for 'termguicolors' and in
 *   the GUI.
 * - Win32: Make terminal used for :!cmd in the GUI work better.  Allow for
 *   redirection.
 *   redirection.  Probably in call to channel_set_pipes().
 * - implement term_setsize()
 * - Copy text in the vterm to the Vim buffer once in a while, so that
 *   completion works.
@@ -3916,6 +3916,57 @@ read_dump_file(FILE *fd, VTermPos *cursor_pos)
    return max_cells;
}

/*
 * Return an allocated string with at least "text_width" "=" characters and
 * "fname" inserted in the middle.
 */
    static char_u *
get_separator(int text_width, char_u *fname)
{
    int	    width = MAX(text_width, curwin->w_width);
    char_u  *textline;
    int	    fname_size;
    char_u  *p = fname;
    int	    i;
    int	    off;

    textline = alloc(width + STRLEN(fname) + 1);
    if (textline == NULL)
	return NULL;

    fname_size = vim_strsize(fname);
    if (fname_size < width - 8)
    {
	/* enough room, don't use the full window width */
	width = MAX(text_width, fname_size + 8);
    }
    else if (fname_size > width - 8)
    {
	/* full name doesn't fit, use only the tail */
	p = gettail(fname);
	fname_size = vim_strsize(p);
    }
    /* skip characters until the name fits */
    while (fname_size > width - 8)
    {
	p += (*mb_ptr2len)(p);
	fname_size = vim_strsize(p);
    }

    for (i = 0; i < (width - fname_size) / 2 - 1; ++i)
	textline[i] = '=';
    textline[i++] = ' ';

    STRCPY(textline + i, p);
    off = STRLEN(textline);
    textline[off] = ' ';
    for (i = 1; i < (width - fname_size) / 2; ++i)
	textline[off + i] = '=';
    textline[off + i] = NUL;

    return textline;
}

/*
 * Common for "term_dumpdiff()" and "term_dumpload()".
 */
@@ -4013,16 +4064,19 @@ term_load_dump(typval_T *argvars, typval_T *rettv, int do_diff)

	term->tl_top_diff_rows = curbuf->b_ml.ml_line_count;

	textline = alloc(width + 1);
	textline = get_separator(width, fname1);
	if (textline == NULL)
	    goto theend;
	for (i = 0; i < width; ++i)
	    textline[i] = '=';
	textline[width] = NUL;
	if (add_empty_scrollback(term, &term->tl_default_color, 0) == OK)
	    ml_append(curbuf->b_ml.ml_line_count, textline, 0, FALSE);
	vim_free(textline);

	textline = get_separator(width, fname2);
	if (textline == NULL)
	    goto theend;
	if (add_empty_scrollback(term, &term->tl_default_color, 0) == OK)
	    ml_append(curbuf->b_ml.ml_line_count, textline, 0, FALSE);
	textline[width] = NUL;

	bot_lnum = curbuf->b_ml.ml_line_count;
	width2 = read_dump_file(fd2, &cursor_pos2);
@@ -4143,6 +4197,9 @@ term_load_dump(typval_T *argvars, typval_T *rettv, int do_diff)
	}

	term->tl_cols = width;

	/* looks better without wrapping */
	curwin->w_p_wrap = 0;
    }

theend:

src/version.c

@@ -762,6 +762,8 @@ static char *(features[]) =

static int included_patches[] =
{   /* Add new patch number below this line */
/**/
    1662,
/**/
    1661,
/**/