[gnome-boxes] Add missing submodule

[Michael Catanzaro <mcatanzaro src gnome org>]

commit d80b5335f235119fc9ce8cb102d3345f89d3aa97
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Wed May 16 12:31:36 2018 -0500

    Add missing submodule
    
    A submodule was added locally, but never committed.

 .gitmodules          | 4 ++--
 subprojects/gtk-frdp | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/.gitmodules b/.gitmodules
index 1f5b62e7..0736948a 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "subprojects/gtk-frdp"]
-    path = subprojects/gtk-frdp
-    url = https://gitlab.gnome.org/felipeborges/gtk-frdp
+       path = subprojects/gtk-frdp
+       url = https://gitlab.gnome.org/felipeborges/gtk-frdp
diff --git a/subprojects/gtk-frdp b/subprojects/gtk-frdp
new file mode 160000
index 00000000..89f2f4c7
--- /dev/null
+++ b/subprojects/gtk-frdp
@@ -0,0 +1 @@
+Subproject commit 89f2f4c75eb0a4a70950ca1254446c9b25f48d6f