Merge branch 'ptrace-5' into 'master'

src/arch/x86_64/interrupt/exception.rs

src/arch/x86_64/interrupt/irq.rs

src/arch/x86_64/interrupt/syscall.rs

src/arch/x86_64/macros.rs

src/common/mod.rs

src/common/unique.rs

src/context/context.rs

src/context/list.rs

src/context/signal.rs

src/context/switch.rs

src/ptrace.rs

src/scheme/mod.rs

src/scheme/proc.rs

src/syscall/debug.rs

src/syscall/process.rs

syscall