pgsql: Further adjust the tests for the hyperbolic functions.

Further adjust the tests for the hyperbolic functions.

It looks like we can leave in most of the test cases for Infinity/NaN
inputs, but buildfarm member jacana gets the wrong answer for acosh(Inf).
It's not worth carrying a variant expected file for that, so just disable
that one test.

Discussion: https://postgr.es/m/E1h3nUY-0000sM-Vf@gemulon.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c43ecdee0fff529ca47a90aea0a6954690af045c

Modified Files
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src/test/regress/expected/float8.out | 8 ++------
src/test/regress/sql/float8.sql      | 3 ++-
2 files changed, 4 insertions(+), 7 deletions(-)