Final excision of libgsystem dependency

Lots and lots of preparation led to this moment - when nothing
apparent changes for users!  Woo!

But seriously, having the extra dependency is a minor annoyance, and
in the big picture I think the libgsystem idea was wrong - we need to
land things in GLib, and use git submodules for API-unstable or
Linux-specific sharing.  For a lot of OSTree, the libgsystem `GFile*`
orientation was also wrong, we really want fd-relative.

Closes: #444
Approved by: jlebon

tests/ci-install.sh

@@ -31,25 +31,6 @@ case "$ci_distro" in
         ;;
 esac
 
-case "$ci_suite" in
-    (jessie)
-        # Add alexl's Debian 8 backport repository to get libgsystem
-        # TODO: remove this when libgsystem is no longer needed
-        $sudo apt-get -y update
-        $sudo apt-get -y install apt-transport-https wget
-        wget -O - https://sdk.gnome.org/apt/debian/conf/alexl.gpg.key | $sudo apt-key add -
-        echo "deb [arch=amd64] https://sdk.gnome.org/apt/debian/ jessie main" | $sudo tee /etc/apt/sources.list.d/flatpak.list
-        ;;
-
-    (trusty|xenial)
-        # Add alexl's Flatpak PPA, again to get libgsystem
-        # TODO: remove this when libgsystem is no longer needed
-        $sudo apt-get -y update
-        $sudo apt-get -y install software-properties-common
-        $sudo add-apt-repository --yes ppa:alexlarsson/flatpak
-        ;;
-esac
-
 case "$ci_distro" in
     (debian|ubuntu)
         # TODO: fetch this list from the Debian packaging git repository?
@@ -77,7 +58,6 @@ case "$ci_distro" in
             libgirepository1.0-dev \
             libglib2.0-dev \
             libgpgme11-dev \
-            libgsystem-dev \
             liblzma-dev \
             libmount-dev \
             libselinux1-dev \

tests/test-checksum.c

@@ -21,7 +21,6 @@
 #include "config.h"
 
 #include "libglnx.h"
-#include "libgsystem.h"
 #include <glib.h>
 #include <stdlib.h>
 #include <gio/gio.h>

tests/test-gpg-verify-result.c

@@ -20,8 +20,8 @@
 
 #include "config.h"
 
-#include <libgsystem.h>
 #include <gpgme.h>
+#include "libglnx.h"
 
 #include "ostree-gpg-verify-result-private.h"