Assembler-friendly includes

[LunarLambda]

It would be nice if libseven's definitions were consumable from assembler without too much extra work. Some things are easy, like providing definitions of VOLADDR etc that work with GNU as.

Everything else would need an __ASSEMBLER__ guard. functions, structs, and most macros aren't super useful as assembler definitions, but enums should somehow be included without making the code too much uglier