Add architecture hooks for saving and restoring the syscall number.
Refactor architecture-dependent headers slightly.
Start isolating x86-generic features into a common x86 header.
ptrace: Make error handling consistent.
Use an error field in 'struct ptrace', and consistently return -1 on
Checkpoint working version.
const fix for memcpy_to_child
Implement memcpy to/from child.
Start to separate ptrace.c into a library.