pgsql: In dpow(), remove redundant check for whether y is an integer.

In dpow(), remove redundant check for whether y is an integer.

I failed to notice that we don't really need to check for y being an
integer in the code path where x = -inf; we already did.

Also make some further cosmetic rearrangements in that spot in hopes
of dodging the seeming compiler bug that buildfarm member fossa is
hitting.  And be consistent about declaring variables as "float8"
not "double", since the pre-existing variables in this function are
like that.

Discussion: https://postgr.es/m/E1jkyFX-0005RR-1Q@gemulon.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/400f16937328d50a7e8d7f0d158f7c92be1da45a

Modified Files
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src/backend/utils/adt/float.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)