Update .good/.prediff for chown file to support cygwin platform.

On cygwin, chown is reporting an "Invalid argument" error instead of the
expected "Operation not permitted" error. The new prediff replaces both
of these with "SYS_ERR", which is what the .good file now expects.
Merge pull request #758 from thomasvandoren/cygwin-regressions

Update .good/.prediff for chown file to support cygwin platform.

On cygwin, chown is reporting an "Invalid argument" error instead of the
expected "Operation not permitted" error. The new prediff replaces both
of these with "SYS_ERR", which is what the .good file now expects.