asyncsafe-spin: Fix race conditions

For several years, I'm seeing occasional failures of the 'test-asyncsafe-spin2' test on native Windows machines with 2 or more CPUs. These failures are caused by the sigprocmask replacement in gnulib, that is not multithread-safe. The first patch fixes that. Then, there is a second race condition

Re: gettext-tools 0.24.1 test-pthread-rwlock fails on Alpine Linux riscv64

So, in the end, I don't see any better action than to add a comment: 2025-05-16 Bruno Haible pthread-rwlock tests: Add a comment. Reported by Natanael Copa in . * tests/test-pthread-rwlock.c:

Re: gettext-tools 0.24.1 test-pthread-rwlock fails on Alpine Linux riscv64

Natanael Copa wrote: > > It passed with chrt --fifo (I had to do it from outside the LXC container): > > > > # time chrt --fifo 10 ./test-pthread-rwlock > > Starting test_rwlock ... OK > > real0m 33.00s > > user6m 50.63s > > sys 0m 16.23s I then wrote: > * On x86_64 (Alpine Linux)