Charlie Jacobsen authored Jan 20, 2016 and Vikram Narayanan committed Oct 26, 2016

Switching over to using registers for syscall args, rather than
being sloppy and using the UTCB. (This was getting silly for
ipc syscalls, because the caller also wants to store data to be
transferred in the UTCB.)

Simple re-factor of lcd putchar into a separate file.