Shrink a local buffer to the size it really needs to be; this is the only
discrepancy found while checking proper {HEX,DECIMAL}_SIZE macro usage, which
is confusing enough.
tweaks and ok jca@, ok guenther@
Do not ask the user to pass either -DB_ENDIAN or -DL_ENDIAN to the compiler,
but rather figure out the endianness from <machine/endian.h> automagically;
help from guenther@

ok jca@ guenther@ beck@ and the rest of the `Buena SSL rampage club'