Don't export __chown

[Roland McGrath]

> I think it is an oversight that __chown@GLIBC_2.1 is exported on i386.  It
> is not explicitly mentioned in libc.map, and nobody has any business to
> use such an internal name anyway.

Agreed.  But we should wait to hear from others if anyone thinks this will
create a problem.

> 	* abilist/libc.abilist: Remove __chown@GLIBC_2.1.

Never hand-edit the .abilist files.  I won't merge such changes.  Always
use the update-abi/check-abi procedure, even though it just does the same
thing.  For i386, you don't need to bother because I will just regenerate
when I put the source changes in.