bpo-46407: Fix long_mod refleak

[Fidget-Spinner]

The PyLongObject from x_divrem isn't used. Introduced in f10dafc.

Before this:

python -m test test_fractions -R 3:3 -m "*FractionTest"
0:00:00 Run tests sequentially
0:00:00 [1/1] test_fractions
beginning 6 repetitions
123456
......
test_fractions leaked [23, 23, 23] references, sum=69
test_fractions leaked [23, 23, 23] memory blocks, sum=69
test_fractions failed (reference leak)

== Tests result: FAILURE ==

After:

0:00:00 Run tests sequentially
0:00:00 [1/1] test_fractions
beginning 6 repetitions
123456
......

== Tests result: SUCCESS ==

https://bugs.python.org/issue46407

[Fidget-Spinner]

CC @pablogsal this (hopefully) fixes the refleak buildbot's numerics tests. Please take a look, thank you!

[markshannon]

Looks good, let's try it with the buildbots.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @markshannon for commit 8140e38 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

[tim-one]

Good catch! The fix looks right.

[markshannon]

@pablogsal @ambv
This fixes the majority of the buildbots.
Please merge this ASAP.