Deprecate -funit-at-a-time

[Robert Dewar]

Richard Guenther wrote:

>> @item -funit-at-a-time
>> @opindex funit-at-a-time
>> This option is left for compatibility reasons. @option{-funit-at-a-time}
>> has no effect, while @option{-fno-unit-at-a-time} imply
>> @option{-fno-toplevel-reder} and @option{-fno-section-anchros}.
> 
> Yes, that's ok.

question, if you have -funit-at-a-time, does that cancel the effect of
-fno-unit-at-a-time earlier on the commmand line?