Added missing ',' installscript.qs

Added missing ',' to packaging-tools/configurations/pkg_tools/
qt.tools.win32_mingw491/meta/installscript.qs

Change-Id: I7b0d202f88208050a6a11fc144072cb1be5b9eb5
Reviewed-by: Antti Kokko <antti.kokko@digia.com>
Reviewed-by: Iikka Eklund <iikka.eklund@theqtcompany.com>