When converting strings to []byte so that they can be used with the tty
io.Writer interface Go calls a runtime method called
"stringtoslicebyte". If the input length exceeds a particular size then
this method will allocate a new []byte and copy the data into it. This
obviously causes our kernel to crash.
To fix this, all early_fmt functions have been changed to iterate any
string arguments and output them to the active TTY one byte at a time.
The kfmt/early package provides a minimal printf implementation that
does not use memory allocations (everything is allocated on the stack).
This implementation can be used to emit debug messages before the memory
manager is initialized.
