thread.c: fix fiber_scheduler_closed and event_thread_end_hooked clobbering
#14128
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…clobbering The variables `fiber_scheduler_closed` and `event_thread_end_hooked` are modified between `setjmp` and `longjmp` calls. Since they are `int`s and their addresses are not used, they can be allocated on registers and get clobbered. Fix by making them `volatile`. This bug can be observed by adding `printf`s for the variables before the `if`s where they are checked, building with Clang, and running `bootstraptest/test_ractor.rb:286`. The second time, the variables should be equal to 1, but they are reset to 0.
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The variables
fiber_scheduler_closedandevent_thread_end_hookedare modified betweensetjmpandlongjmpcalls. Since they areints and their addresses are not used, they can be allocated on registers and get clobbered. Fix by making themvolatile.This bug can be observed by adding
printfs for the variables before theifs where they are checked, building with Clang, and runningbootstraptest/test_ractor.rb:286. The second time, the variables should be equal to 1, but they are reset to 0.