--enable-depend by default (was Re: Patch: fix lock contention for HASHHDR.mutex)

[ A change as significant as this should not be debated in a thread with
a title that suggests it's of interest to only one or two people ]

> On Wed, Dec 30, 2015 at 5:44 PM, Andres Freund <andres@anarazel.de> wrote:
>> I still maintain that --enable-depend should be on by default. We're
>> absurdly optimizing towards saving a handful of cycles in scenarios
>> which are usually bottlenecked by other things (build boxes spend more
>> times on tests and such)

Nonsense.  The buildfarm will simply get slower, and at least for my
animals it's too damn slow already.  We could fix that by having the
buildfarm script automatically add --disable-depend; but if we're going
to change this, we should roll out that script update BEFORE we change
it, not after.
        regards, tom lane