bloom_filter: fix overflow for large filters
bloom_filter: fix overflow for large filters

We use ::abs(), which has an int parameter, on long arguments, resulting
in incorrect results.

Switch to std::abs() instead, which has the correct overloads.

Fixes #1494.

Message-Id: <d7165ee585c82821a9dfa1a75b4ce27b00102e40@scylladb.com>

raphaelsc/scylla,kjniemi/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,raphaelsc/scylla,raphaelsc/scylla,avikivity/scylla,kjniemi/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,duarten/scylla,duarten/scylla,avikivity/scylla,kjniemi/scylla