glocalfile: Only use O_DIRECTORY if available

Solaris 10 for example doesn't have it.

https://bugzilla.gnome.org/show_bug.cgi?id=708860
gdesktopappinfo: Add missing annotations

Add missing (allow-none) annotations to
g_desktop_app_info_launch_uris_as_manager(). Tested with

  python -c "from gi.repository import GLib, Gio; Gio.DesktopAppInfo.new('gcalctool.desktop').launch_uris_as_manager([], None, GLib.SpawnFlags.SEARCH_PATH|GLib.SpawnFlags.STDOUT_TO_DEV_NULL, None, None, None, None)"

which is necessary to do a launch_uris() without leaking stdout.

https://launchpad.net/bugs/1259721
gio/gdbusaddress.c: Fix RunDLL call for Windows/x64 builds

On x64 builds under both Visual C++ and MinGW-64, the correct symbol for
the RunDLL call is g_win32_run_session_bus, so this will silence the
annoying RunDLL error for x64 MinGW builds as well, and will allow this
call to be executed more than once.

Thanks to Tarnyko for pointing this out.