MAKE-ARRAY: handle CHARACTER-SET-TYPE.

CHARACTER-SET-TYPE, i.e., (member #\a #\c) or (eql #\d) wasn't
considered by SB-IMPL::%VECTOR-WIDETAG-AND-N-BITS.

Fixes lp#1392068.
More compact character case tables.

Instead of using vectors with conses use a flat vector twice as large,
which takes 1/3 less space.

Also fixes lp#1392068.
Random genesis cleanup / comment improvement
Add syscall/sysret instructions.
Add some notes and an existing attempt at direct syscalls.