[evince] backend: Fix compilation warning in dvi backend

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

commit ba23ea45548c5b1c82b946170c3aa9e684c38bbd
Author: Germán Poo-Caamaño <gpoo gnome org>
Date:   Sun Jun 21 21:36:43 2020 -0400

    backend: Fix compilation warning in dvi backend
    
    Initilize variable.

 backend/dvi/mdvi-lib/pagesel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/backend/dvi/mdvi-lib/pagesel.c b/backend/dvi/mdvi-lib/pagesel.c
index 5a153955..11b318f5 100644
--- a/backend/dvi/mdvi-lib/pagesel.c
+++ b/backend/dvi/mdvi-lib/pagesel.c
@@ -198,7 +198,7 @@ DviPageSpec *mdvi_parse_page_spec(const char *format)
        DviRange *range;
        int     count;
        int     i;
-       char    *ptr;
+       char    *ptr = NULL;
        
        spec = xnalloc(struct _DviPageSpec *, 11);
        for(i = 0; i < 11; i++)