Relicense files for which I am the sole author (as identified by
util/relicense.pl).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

The implementation of strtoul() has a partially unknown provenance.
Rewrite this code to avoid potential licensing uncertainty.

Since we now use -ffunction-sections, there is no need to place
strtoull() in a separate file from strtoul().

Signed-off-by: Michael Brown <mcb30@ipxe.org>