Implement PTRACE_GET_SYSCALL_INFO decoder

Implement PTRACE_GET_SYSCALL_INFO decoder

* defs.h (audit_arch): New prototype.
* process.c: Include "ptrace_syscall_info.h".
(SYS_FUNC(ptrace)) <PTRACE_GET_SYSCALL_INFO>: Call
print_ptrace_syscall_info on exiting syscall.
* ptrace_syscall_info.h (print_ptrace_syscall_info): New prototype.
* ptrace_syscall_info.c: Include "print_fields.h" and
"xlat/ptrace_syscall_info_op.h".
(print_ptrace_syscall_info): New function.
* xlat/ptrace_syscall_info_op.in: New file.
* tests/ptrace_syscall_info.c: New file.
* tests/gen_tests.in (ptrace_syscall_info): New test.
* tests/pure_executables.list: Add ptrace_syscall_info.
* tests/.gitignore: Likewise.