MFC r302448:
Don't forget to set sa->narg for CloudABI system calls. It turns out that this value is not used within the system call code under normal conditions, except when using tracing tools like ktrace. If we forget to set this value, it is set to random garbage. This may cause ktrace to hang indefinitely, making it impossible to kill.
Approved by: re@
Reported by: Michael Plass
PR: 210800