cur_console is NULL when copy_font() is first called from scinit(). This
is apparently harmless when scinit() is called early from sccninit() -
page 0 is apparently mapped r/w then, and 0->status contains suitable
garbage. However, when there is a serial console, scinit() is first
called from scattach() when the page tables are completely initialized,
so the NULL pointer causes a panic.
Submitted by: bruce
b293f5b41c