[3.12] Make test_fcntl quiet (GH-108758)

[miss-islington]

Running test_fcntl logs two "struct.pack: ..." lines because
multiprocessing imports test_fcntl twice with
test.support.verbose=1. Move get_lockdata() inside TestFcntl test
case and only call it where it's needed, to stop logging these lines.
(cherry picked from commit 23f54c1)

Co-authored-by: Victor Stinner [email protected]

[vstinner]

LGTM, good bot.

[vstinner]

Before:

$ ./python -m test test_fcntl
0:00:00 load avg: 0.97 Run tests sequentially
0:00:00 load avg: 0.97 [1/1] test_fcntl
struct.pack:  b'\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
struct.pack:  b'\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

== Tests result: SUCCESS ==

1 test OK.

Total duration: 954 ms
Tests result: SUCCESS

After:

$ ./python -m test test_fcntl
0:00:00 load avg: 1.05 Run tests sequentially
0:00:00 load avg: 1.05 [1/1] test_fcntl

== Tests result: SUCCESS ==

1 test OK.

Total duration: 778 ms
Tests result: SUCCESS

The two struct.pack: b'\x01\x00(...)' lines are gone.