Re: no test programs in contrib

Here's a patch.  This creates a new subdir src/test/modules and places
the five initially proposed modules in there.  They continue to have
their makefile with the same ifdef USE_PGXS pattern; they are no longer
installed by default.

Because many of them had either "test" in their names or some other
now-useless particle, I renamed them:

worker_spi    ->     bgworker
test_decoding    ->    logical_decoding
dummy_seclabel    ->    seclabel
test_shm_mq    ->    shm_mq
test_parser    ->    tsparser

The renaming is not complete: the extensions continue to have the old
names, for instance.  If the consensus is to rename them completely I
can finish that, or we can decide to keep the original names, but they
all seem inappropriate to me.

I haven't done anything about documentation.  I thought a new chapter
after "Additional Supplied Modules", perhaps entitled "Additional Sample
Modules" would be appropriate.

I tweaked make targets check, installcheck, installcheck-world,
check-world: they all run the additional tests now.  For buildfarm, the
client code will need to be updated to have a new stage for
src/test/modules running "make check".

I haven't touched MSVC yet.

Opinions on this approach please?

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
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