[gimp] app: silence gcc warning

[Øyvind Kolås <ok src gnome org>]

commit 81e1e3967d0395c2f10ffc312c8409327041cf0c
Author: Massimo Valentini <mvalentini src gnome org>
Date:   Sat Apr 7 14:30:30 2018 +0200

    app: silence gcc warning
    
    gimp-templates.c:143:15: warning: ‘strncpy’ output truncated before terminating nul copying 3 bytes from 
a string of the same length [-Wstringop-truncation]
                   strncpy (dpi, "ppi", 3);
                   ^~~~~~~~~~~~~~~~~~~~~~~

 app/core/gimp-templates.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/app/core/gimp-templates.c b/app/core/gimp-templates.c
index a3c9393..f5a3643 100644
--- a/app/core/gimp-templates.c
+++ b/app/core/gimp-templates.c
@@ -140,7 +140,7 @@ gimp_templates_migrate_get_child_by_name (GimpContainer *container,
 
           if (dpi)
             {
-              strncpy (dpi, "ppi", 3);
+              strncpy (dpi, "ppi", 4);
 
               g_print ("replaced: %s\n", str1);