This patch shrinks boot2 a little.
This patch shrinks boot2 a little.

o    It switches kname to be just a pointer instead of an array
     thus avoiding a couple of memcpy()s.

o    It changes ioctl to unsigned from uint8_t.

o    It changes the second keyhit limit to 3 seconds from 5
     so that constant propagation can take place.

o    It changes the ticks overflow computation as suggested by bde@.

o    It removes bi_basemem/bi_extmem/bi_memsizes_valid setting from
     bootinfo as it is unused.

Reviewed by: jhb

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase