Tweak syscall code so that sys_* declarations can include arguments.
Tweak syscall code so that sys_* declarations can include arguments.

scale-amd64 passes all "argint" syscall arguments via registers, so
it might be more convenient to pass them all to the sys_* functions
(instead of reading them via argint).

bowlofstew/sv6,bowlofstew/sv6,bowlofstew/sv6,aclements/sv6,bowlofstew/sv6,aclements/sv6,aclements/sv6,aclements/sv6,aclements/sv6,bowlofstew/sv6