[evince/gnome-3-36] backends: Fix -Wformat-zero-length warning

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

commit bc6c93734db3d3614c371ccd5fe0595d7074c3ac
Author: Germán Poo-Caamaño <gpoo gnome org>
Date:   Sat May 30 11:29:37 2020 -0400

    backends: Fix -Wformat-zero-length warning
    
    The way we used mdvi-lib it should be safe to just silent
    printing a `noop` command with a new line. The code does
    not even seem to use that function.

 backend/dvi/mdvi-lib/dviread.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/backend/dvi/mdvi-lib/dviread.c b/backend/dvi/mdvi-lib/dviread.c
index d0143205..b33ad9a1 100644
--- a/backend/dvi/mdvi-lib/dviread.c
+++ b/backend/dvi/mdvi-lib/dviread.c
@@ -1329,7 +1329,7 @@ int       set_rule(DviContext *dvi, int opcode)
 
 int    no_op(DviContext *dvi, int opcode)
 {
-       SHOWCMD((dvi, "noop", -1, ""));
+       SHOWCMD((dvi, "noop", -1, "\n"));
        return 0;
 }