Move the standard definitions of constants, variously-sized ints,limits into
respective architecture specific files. com32/include/bitsize holds the standard
header files that in turn include bitsize32 or bitsize64 based on the architecture.
The makefiles should build pick the right ones based on architecture.

Files com32/include/sys/cpu.h, com32/include/sys/bitops.h now have
architecture specific files underneath to define relevant macros definitions.

com32/include/setjmp.h has architecture specific counterparts underneath.

ssize_t in dos/stdlib.h is appropriately defined based on architecture to be able
to support building for 32bit and 64bit environments.

Remanants of the unused old i386-only files, if any, need to be pruned.