fix dangling pointers in x32 syscall timespec fixup code

the lifetime of compound literals is the block in which they appear.
the temporary struct __timespec_kernel objects created as compound
literals no longer existed at the time their addresses were passed to
the kernel.

fix x32 syscall arch.h timespec fixup code

it's legal to call the __syscall functions with more arguments than
necessary, and the __syscall_cp cancel dummy impl. does just that.

thus we must insert the switch for all possible syscalls numbers
into all of the syscallN inline functions.

mostly-cosmetic fixups to x32 port merge

x32 port (diff against vanilla x86_64)

import vanilla x86_64 code as x32