threads: during abrupt thread-exit, cleanup anyways

[vtjnash]

Closes #47590 (pthread_cancel still forbidden though, since async mode will corrupt the process, and synchronously tested is just a slow implementation of a boolean)

Refs #47201 (only deals with thread exit, not other case where this is an issue, like cfunction exit and gc-safe-leave)

May help #46537, by blocking jl_wake_libuv before uv_library_shutdown, and other tweaks to GC mode. For example:

[4011824] signal (6.-6): Aborted
gsignal at /lib/x86_64-linux-gnu/libc.so.6 (unknown line) abort at /lib/x86_64-linux-gnu/libc.so.6 (unknown line) uv__async_send at /workspace/srcdir/libuv/src/unix/async.c:198 uv_async_send at /workspace/srcdir/libuv/src/unix/async.c:73 jl_wake_libuv at /data/vtjnash/julia1/src/jl_uv.c:44 [inlined] JL_UV_LOCK at /data/vtjnash/julia1/src/jl_uv.c:64 [inlined] ijl_iolock_begin at /data/vtjnash/julia1/src/jl_uv.c:72 iolock_begin at ./libuv.jl:48 [inlined]
_trywait at ./asyncevent.jl:140
wait at ./asyncevent.jl:155 [inlined]
profile_printing_listener at /data/vtjnash/julia1/usr/share/julia/stdlib/v1.10/Profile/src/Profile.jl:39 jfptr_YY.3_58617 at /data/vtjnash/julia1/usr/lib/julia/sys.so (unknown line) _jl_invoke at /data/vtjnash/julia1/src/gf.c:2665 [inlined] ijl_apply_generic at /data/vtjnash/julia1/src/gf.c:2866 jl_apply at /data/vtjnash/julia1/src/julia.h:1870 [inlined] start_task at /data/vtjnash/julia1/src/task.c:1093 Aborted

Fixes #37400

[maleadt]

Thanks, does indeed fix #47590.

pthread_cancel still forbidden though, since async mode will corrupt the process, and synchronously tested is just a slow implementation of a boolean

So synchronous/deferred pthread_cancel isn't forbidden, and indeed seems to work (this matter when e.g. we don't control the code that manages threads, but we can set our own thread to PTHREAD_CANCEL_DEFERRED).

[vtjnash]

deferred is the default, but it would need to be used in concert with PTHREAD_CANCEL_DISABLE too, since it will corrupt the mutex state of any correctly written multi-threaded process, and thus should lead to a guaranteed deadlock.

[vtjnash]

boo

Dates/conversions                                (5) |         failed at 2023-01-11T13:59:58.377
Test Failed at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-macmini-x64-1.0/build/default-macmini-x64-1-0/julialang/julia-master/julia-6034d94057/share/julia/stdlib/v1.10/Dates/test/conversions.jl:63
  Expression: abs(Dates.now() - now(Dates.UTC)) < Dates.Second(1)
   Evaluated: Dates.Millisecond(1001) < Dates.Second(1)

[gbaraldi]

Should we make that a bit more robust? :)