gh-127604: Allow faulthandler to dumpC stack on MacOS

[pablogsal]

• Issue: Add a way of printing a C backtrace to faulthandler #127604

[pablogsal]

❯ ./python.exe -m test test_faulthandler -v | grep c_stack
test_dump_c_stack (test.test_faulthandler.FaultHandlerTests.test_dump_c_stack) ... ok
test_dump_c_stack_file (test.test_faulthandler.FaultHandlerTests.test_dump_c_stack_file) ... ok

~/github/python/main gh-127604* 17s
❯ uname -a
Darwin HWJ59XLTF9 24.4.0 Darwin Kernel Version 24.4.0: Fri Apr 11 18:33:47 PDT 2025; root:xnu-11417.101.15~117/RELEASE_ARM64_T6000 arm64

[ZeroIntensity]

I don't have a Mac to test this on, so I'll trust that you've tested this locally. The tests only require that it either spits out <cannot get backtrace> or the actual C backtrace.

[pablogsal]

I don't have a Mac to test this on, so I'll trust that you've tested this locally. The tests only require that it either spits out <cannot get backtrace> or the actual C backtrace.

My previous comment was proving exactly that :)