[arch-releng] [releng-scripts]: add dosfstools to releng-chroot-manager

- extrapkgs="vim mc base-devel git svn cvs mkinitcpio libisoburn squashfs-tools devtools libui-sh" + extrapkgs="vim mc base-devel git svn cvs mkinitcpio libisoburn squashfs-tools dosfstools devtools libui-sh" otherwise x86_64 isos does not build. -- Gerardo Exequiel Pozzi \cos^2\alpha + \sin^2\alpha = 1