auto-generated files and deletions are in another CL.
goals for new syscall:
* automate as much as possible
* do not let clients do unsafe things
* use simple types (int not int64)
* fewer files
the files are renamed from foo_amd64_linux to foo_linux_amd64,
both because it reads better (all the linux are related, all the amd64 less so)
and because it made it easier to replace the existing ones.
R=r
DELTA=2336 (2260 added, 6 deleted, 70 changed)
OCL=29709
CL=29723
