Currently ANY implementation fabricates new types dynamically.
This is something we don't do anywhere else, generally types
come from compiler and all are static.
Dynamic types will conflict with use of Ref in Arg optimization.
Move ANY types creation into compiler.
Update #1580
When we build a list of resource constructors we over and over iterate through
all types in a syscall to find resource types. Speed it up by iterating only
once to build a list of constructors for each resource and then reuse it.
This significantly speeds up syz-exeprog startup time on Raspberry Pi Zero.
Currently a call that both accepts and creates a resource
self-justifies itself and thus is always enabled.
A good example is accept call. Accepts are always self-enable
and thus enable all other syscalls that work with the socket.
Calculate TransitivelyEnabledCalls in the opposite direction
to resolve this. Start with empty set of enable syscalls,
then enable syscalls that don't accept any resources,
then enable syscalls that accept resources created by the
previous batch of syscalls, and so on.
This prevents self-enablement of accept.
Now each prog function accepts the desired target explicitly.
No global, implicit state involved.
This is much cleaner and allows cross-OS/arch testing, etc.
Large overhaul moves syscalls and arg types from sys to prog.
Sys package now depends on prog and contains only generated
descriptions of syscalls.
Introduce prog.Target type that encapsulates all targer properties,
like syscall list, ptr/page size, etc. Also moves OS-dependent pieces
like mmap call generation from prog to sys.
Update #191
