OK, I had something strange with my mounts but I found the suggestion somewhere to do: cat /proc/mounts > /etc/mtab and that worked (mtab was empty, fstab too).
Now mount shows: selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime) so I did mount -o remount,ro /sys/fs/selinux And I was able to install binutils finally with no selinux error. But it seems to have thrown Android for a loop (or maybe it's the read only mount). In a few minutes the terminal emulator went blank, none of my icons do anything. I can't even turn it off, it hangs saying "shutting down" with a little loopy progress indicator going around and around. My Micro CPU Monitor app is still going. So I'll let it sit until the battery runs down. My guess is that by default /sys/fs/selinux will get mounted read/write on power up and everything will be normal again. I guess I should have set it back read/write as soon as I was done. I have only power and volume buttons, they don't seem to do anything useful. 100% battery charge too, so a long wait. Maybe I should scrap this and reinstall. -- Credit is the root of all evil. - AB1JX