[gedit/gnome-3-30] Use absolute path for libgd submodule

[Ken VanDine <kvandine src gnome org>]

commit e1dfc76ad61cf01e836fbc5b78c4449c02930a5f
Author: Ken VanDine <ken vandine canonical com>
Date:   Wed Feb 6 15:05:42 2019 -0500

    Use absolute path for libgd submodule

 .gitmodules | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitmodules b/.gitmodules
index bf030e9fb..66989de51 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "libgd"]
        path = libgd
-       url = ../libgd.git
+       url = https://gitlab.gnome.org/GNOME/libgd.git