pgsql: Suppress -0 in the C field of lines computed by line_construct_p

Suppress -0 in the C field of lines computed by line_construct_pts().

It's not entirely clear why some PPC machines are generating -0 here, since
the underlying computation should be exactly 0 - 0.  Perhaps there's some
wider-than-nominal-precision calculations happening?  Anyway, the best way
to avoid platform-dependent results seems to be to explicitly reset -0 to
regular zero.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/43fe90f66a0b200f6c32507428349afb45f661ca

Modified Files
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src/backend/utils/adt/geo_ops.c |    3 +++
1 file changed, 3 insertions(+)