support for calling Linux syscalls directly

[Roland McGrath]

I like hpa's plan.  My strongest objection to adding more things to libc is
about adding to the ABI.  So libc_nonshared.a is less objectionable.  But I
would prefer that we avoid getting involved at all in the maintenance
burden of obscure kernel interfaces.  Things that are really meant to be
used commonly by many normal/mostly-portable applications are a different
story and can be considered case by case.


Thanks,
Roland