[evince] dvi: Minus sign doesn't appear with mathdesign fonts

[Germán Poo-Caamaño <gpoo src gnome org>]

commit 69405e25a4e557ff3ec9e8b52a3cb54a024dc11f
Author: David C. Sterratt <david c sterratt ed ac uk>
Date:   Sat Aug 15 14:29:02 2020 +0100

    dvi: Minus sign doesn't appear with mathdesign fonts
    
    The minus sign does not appear in the dvi file that results from
    latex'ing:
    
      \documentclass{article}
      \usepackage[mdugm]{mathdesign}
      \begin{document}
      $x-y$
      \end{document}
    
    Evince gives the following warning when rendering the dvi file:
    
      Warning: requested character 0 does not exist in `mdugmr7y'.
    
    The offset of the DviFontChar for the minus sign is 0, so that
    glyph_present() reports the character as being absent, when it is in
    fact present. This patch fixes the problem by only checking the
    DviFontChar pointer is not null, removing the test that the content
    of DviFontChar is 0.
    
    Fixes #1477

 backend/dvi/mdvi-lib/font.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/backend/dvi/mdvi-lib/font.c b/backend/dvi/mdvi-lib/font.c
index 2f655df0..154c4136 100644
--- a/backend/dvi/mdvi-lib/font.c
+++ b/backend/dvi/mdvi-lib/font.c
@@ -354,7 +354,7 @@ again:
        
        /* get the unscaled glyph, maybe loading it from disk */
        ch = FONTCHAR(font, code);
-       if(!ch || !glyph_present(ch))
+       if(!ch)
                return NULL;
        if(!ch->loaded && load_one_glyph(dvi, font, code) == -1) {
                if(font->chars == NULL) {