pgsql: Add basic spinlock tests to regression tests.

Add basic spinlock tests to regression tests.

As s_lock_test, the already existing test for spinlocks, isn't run in
an automated fashion (and doesn't test a normal backend environment),
adding tests that are run as part of a normal regression run is a good
idea. Particularly in light of several recent and upcoming spinlock
related fixes.

Currently the new tests are run as part of the pre-existing
test_atomic_ops() test. That perhaps can be quibbled about, but for
now seems ok.

The only operations that s_lock_test tests but the new tests don't are
the detection of a stuck spinlock and S_LOCK_FREE (which is otherwise
unused, not implemented on all platforms, and will be removed).

This currently contains a test for more than INT_MAX spinlocks (only
run with --disable-spinlocks), to ensure the recent commit fixing a
bug with more than INT_MAX spinlock initializations is correct. That
test is somewhat slow, so we might want to disable it after a few
days.

It might be worth retiring s_lock_test after this. The added coverage
of a stuck spinlock probably isn't worth the added complexity?

Author: Andres Freund
Discussion: /messages/by-id/20200606023103.avzrctgv7476xj7i@alap3.anarazel.de

Branch
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REL9_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/7e91f90a8ed4af18f4d2a3cb1b657b4296e2e710

Modified Files
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src/test/regress/regress.c | 109 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 109 insertions(+)