Drop libgsystem dependency, major internals rework

I want to drop libgsystem from the world, this is one of the last holdouts. We
now require modern GLib and libsystemd. A side effect of this is that we're
likely to break some of the gnome-continuous journald integration.

Makefile-tests.am

@@ -18,5 +18,5 @@
 bin_PROGRAMS += gnome-desktop-testing-runner
 gnome_desktop_testing_runner_SOURCES = src/gnome-desktop-testing-runner.c
 gnome_desktop_testing_runner_CPPFLAGS = $(AM_CPPFLAGS)
-gnome_desktop_testing_runner_CFLAGS = $(BUILDDEP_GDT_CFLAGS) $(SYSTEMD_JOURNAL_CFLAGS)
-gnome_desktop_testing_runner_LDADD = $(BUILDDEP_GDT_LIBS) $(SYSTEMD_JOURNAL_LIBS)
+gnome_desktop_testing_runner_CFLAGS = $(BUILDDEP_GDT_CFLAGS)
+gnome_desktop_testing_runner_LDADD = $(BUILDDEP_GDT_LIBS)

configure.ac

@@ -27,20 +27,9 @@ AC_SUBST(WARN_CFLAGS)
 LT_PREREQ([2.2.4])
 LT_INIT([disable-static])
 
-PKG_CHECK_MODULES(BUILDDEP_GDT, [gio-unix-2.0 >= 2.34.0 libgsystem])
+PKG_CHECK_MODULES(BUILDDEP_GDT, [gio-unix-2.0 >= 2.34.0 libsystemd])
 GIO_UNIX_CFLAGS="$GIO_UNIX_CFLAGS -DGLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_36 -DGLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_36"
 
-AC_ARG_WITH(systemd-journal,
-	    AS_HELP_STRING([--without-systemd-journal], [Use systemd @<:@default=auto@:>@]),
-	    [], [with_systemd_journal=auto])
-AS_IF([test x$with_systemd_journal != xno], [
-  PKG_CHECK_MODULES([SYSTEMD_JOURNAL], [libsystemd], have_systemd_journal=yes, have_systemd_journal=no)
-  ])
-AM_CONDITIONAL(ENABLE_SYSTEMD_JOURNAL, test x$have_systemd_journal = xyes)
-AS_IF([test x$have_systemd_journal = xyes], [
-  AC_DEFINE([ENABLE_SYSTEMD_JOURNAL],[1],[Define if you want to build with systemd journal support])
-])
-
 AC_CONFIG_FILES([
 Makefile
 ])