No generic 10.4 binary tarballs compatible with RHEL6

With 10.4 the old generic tarball has been removed, and only the -glibc_214 and -systemd tarballs are still available for download.

RHEL 6 still comes with glibc 2.12 though, and so neither of the current binary tarballs work there. RHEL 6 itself is supported by RedHat until November 2020, and we also still have 10.4 RPMs for it, so we should have compatible 10.4 binary tarballs, too ...