[gnome-builder] flatpak: fix arch comparison

[Christian Hergert <chergert src gnome org>]

commit dadea3826b84baf34392ef392751c6db73242b17
Author: Christian Hergert <chergert redhat com>
Date:   Thu Mar 14 11:03:30 2019 -0700

    flatpak: fix arch comparison

 src/plugins/flatpak/gbp-flatpak-manifest.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/plugins/flatpak/gbp-flatpak-manifest.c b/src/plugins/flatpak/gbp-flatpak-manifest.c
index b3f55ceb6..c5a8fff6f 100644
--- a/src/plugins/flatpak/gbp-flatpak-manifest.c
+++ b/src/plugins/flatpak/gbp-flatpak-manifest.c
@@ -1010,7 +1010,7 @@ gbp_flatpak_manifest_get_runtimes (GbpFlatpakManifest *self,
 
   ar = g_ptr_array_new ();
 
-  if (for_arch != NULL)
+  if (for_arch == NULL)
     for_arch = flatpak_get_default_arch ();
 
   if (self->runtime_version != NULL)