policy on __libc_*

[Roland McGrath]

Regardless of the other bickering, I don't think I got a clear answer on
the question of what the general policy is about __libc_foo names.  I've
just __libc_ified lseek, open, and fcntl for the hurd since other things
have come to use those.  This is a non-issue for the hurd, since
cancellation is handled entirely differently (the __libc_foo, __foo, and
foo names are all aliases for the same thing regardless), but it would be
nice to know what to expect from the os-independent parts of libc.