bug#12899: Build failure from latest master

[Jim Meyering]

Stefano Lattarini wrote:

> Hi Paul, thanks for the quick feedback.
>
> On 11/15/2012 10:03 PM, Paul Eggert wrote:
>> Thanks, wouldn't the following be a bit cleaner,
>> since MAINTAINERCLEANFILES contains BUILT_SOURCES?
>>
> Possibly yes, but since this behaviour is not documented in the Automake
> manual, I'd marginally (60-40) prefer not rely on it.  Not a big deal
> in any case, so feel free to mend my patch if you like, with my ACK.

I too prefer to use BUILT_SOURCES, and using it here is
consistent with the numerous other uses in that file.

Which behavior is not documented?
The MAINTAINERCLEANFILES-containing-BUILT_SOURCES is done
via this in src/local.mk:

  MAINTAINERCLEANFILES += $(BUILT_SOURCES)