pgsql: Avoid use of float arithmetic in bipartite_match.c.

Avoid use of float arithmetic in bipartite_match.c.

Since the distances used in this algorithm are small integers (not more
than the size of the U set, in fact), there is no good reason to use float
arithmetic for them. Use short ints instead: they're smaller, faster, and
require no special portability assumptions.

Per testing by Greg Stark, which disclosed that the code got into an
infinite loop on VAX for lack of IEEE-style float infinities. We don't
really care all that much whether Postgres can run on a VAX anymore,
but there seems sufficient reason to change this code anyway.

In passing, make a few other small adjustments to make the code match
usual Postgres coding style a bit better.

Branch
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REL9_5_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/4022f94c350f96fc5feff0503d3e2f2f6f9086cc

Modified Files
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src/backend/lib/bipartite_match.c | 75 +++++++++++++++++++++++--------------
src/include/lib/bipartite_match.h | 16 ++++----
2 files changed, 55 insertions(+), 36 deletions(-)