pgsql: Cast result of i64abs() back to int64

Cast result of i64abs() back to int64

Without the cast, the return type could be long or long long,
depending on what int64 is underneath.  This doesn't affect code
correctness, but it could result in format-mismatch warnings when
attempting to printf such values using PRId64.

Reported-by: Thomas Munro <thomas.munro@gmail.com>
Discussion:
https://www.postgresql.org/message-id/flat/CA+hUKGJc4s+Wyb3EFOQNN9VVK+Qv40r2LK41o9PkS9ThxviTvQ@mail.gmail.com

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/2247281c470502c799fc2153a3583c025e894a9c

Modified Files
--------------
src/include/c.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)