[coreboot] libpayload: Add -Os to the CFLAGS

[Segher Boessenkool]

> I'd try to reuse strncpy() so that any optimizations need to be done
> in as few places as possible.
>
> Save strlen() and just append the 0.

Just do strlen() + 1, heh.

Or do Uwe's thing (without the parentheses around d and s, and
with the loop body on a separate line, coding standards...) if
you are terribly worried about performance here.  Or just import
from some existing C library, no need to reinvent the wheel,
and some of these functions can be quite tricky to get right ;-)


Segher