Back off output precision in circle.sql regression test.

Back off output precision in circle.sql regression test.

We were setting extra_float_digits = 0 to avoid platform-dependent
output in this test, but that's still able to expose platform-specific
roundoff behavior in some new test cases added by commit a3d284485,
as reported by Peter Eisentraut.  Reduce it to -1 to hide that.

(Over in geometry.sql, we're using -3, which is an ancient decision
dating to 337f73b1b.  I wonder whether that's overkill now.  But
there's probably little value in trying to change it.)

Back-patch to v12 where a3d284485 came in; there's no evidence that
we have any platform-dependent issues here before that.

Discussion: http://postgr.es/m/15551268-e224-aa46-084a-124b64095ee3@2ndquadrant.com