aarch64: exception management and clone fixups

src/arch/aarch64/init/pre_kstart/helpers/vectors.S

src/arch/aarch64/interrupt/handler.rs

src/arch/aarch64/interrupt/mod.rs

src/arch/aarch64/interrupt/syscall.rs

src/arch/aarch64/interrupt/unhandled_exceptions.rs

src/context/arch/aarch64.rs

src/syscall/process.rs