OK, I've updated the patch so configure takes a --with-builtin-sources
argument, which is off by default.

On 28 February 2016 at 15:38, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Paul Eggert <eggert@cs.ucla.edu>
>> Date: Sat, 27 Feb 2016 19:34:25 -0800
>>
>> Wilfred Hughes wrote:
>> > Does this seem reasonable? Is there some configure flag that does this
>> > already?
>>
>> It seems reasonable, for the same reason we install .el files.
>
> Installing C sources could be an option, off by default.  But
> installing always or by default is something we shouldn't do, IMO.
> Many users will not want or need that.
>
>