bootstrap.conf: add threadlib module

It is pulled in by tests and used by our build system as well.
Make an explicit dependency on threadlib.  This can be later removed
by using GLib GThread.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

bootstrap.conf

@@ -58,6 +58,8 @@ gnulib_modules="$gnulib_modules sigaction"
 gnulib_modules="$gnulib_modules sigpipe"
 # -> open code conditional or use GIO GFileInfo
 gnulib_modules="$gnulib_modules stat-time"
+# -> GThread
+gnulib_modules="$gnulib_modules threadlib"
 # -> remove use or open-code it. possibly add to glib
 gnulib_modules="$gnulib_modules strchrnul"
 # -> g_strsplit