4-post x86-64 interpreter work: all 0-6 arg syscalls in 32 bytes,
embed interpreter inside words with 3-byte overhead (AD lodsd + FF E0
jmp rax), force lower 32-bit but keep 64-bit, pack interpreted forth
words in aligned 8-bytes. Tangent post 4 from @NOTimothyLottes
self-replying about custom bytecode + on-load decompression.
