Clean up thread-local error stacks in all threads

[mattjala]

When threadsafety is enabled, threadlocal error stacks in threads that don't call H5_term_library do not have any error records stored on them cleaned up properly. This leads to leaked memory and, before the recent changes to H5E, an infinite loop during library close.

Set of changes:

• Cleanup threadlocal error stack at individual thread exit time
• Rename H5E__clear_stack() to H5E__destroy_stack() to contrast its intention with H5E_clear_stack()
• Add a ttsafe test

This PR was originally much more complex, and the below description is out-of-date.

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Fixing this is complicated by the fact that H5TS's cleanup is currently performed after every individual module is terminated. In order for the records to be released properly, H5TS must terminate before H5E and after H5CX, necessitating rearranging the termination order. As a side effect, most H5TS resources that were previously set up and released on a per-process basis (H5TS_tinfo_mtx_s, H5TS_api_info_p, H5TS_thrd_info_key_g) are now handled per-thread.

This is currently a draft PR due to an issue with thread once macros on MacOS builds. The flag the library uses to perform only one initialization of H5TS across all threads, H5TS_first_thread_init_s, is not currently cleaned up at library close. If the library is closed and re-opened, the library will see the old value and not properly initialize H5TS.

This can be solved on most systems by re-initializing H5TS_first_init_s = H5TS_ONCE_INITIALIZER during H5TS termination. However, it appears that on MacOS, the PTHREAD_ONCE_INIT macro is defined in a manner that causes problems with this approach:

 In file included from /Users/runner/work/hdf5/hdf5/src/H5private.h:65,
                 from /Users/runner/work/hdf5/hdf5/src/H5TSint.c:35:
/Users/runner/work/hdf5/hdf5/src/H5TSint.c: In function 'H5TS_term_package':
/Users/runner/work/hdf5/hdf5/src/H5TSprivate.h:71:36: error: expected expression before '{' token
   71 | #define H5TS_ONCE_INITIALIZER      PTHREAD_ONCE_INIT
      |                                    ^~~~~~~~~~~~~~~~~
/Users/runner/work/hdf5/hdf5/src/H5TSint.c:151:25: note: in expansion of macro 'H5TS_ONCE_INITIALIZER'
  151 |     H5TS_first_init_s = H5TS_ONCE_INITIALIZER;
      |                         ^~~~~~~~~~~~~~~~~~~~~

My best guess is that MacOS enforces the requirement that PTHREAD_ONCE_INIT only be used for static initializations, and this initialization during termination is dynamic. Windows threads have both a static and dynamic once flag initializer (INIT_ONCE_STATIC_INIT and InitOnceInitialize) but I haven't been able to find a dynamic counterpart for pthreads.

[qkoziol]

I don't think that most of the library changes should go in. I've added comments, but I'm also happy to talk in-person or on a call.

[mattjala]

Vastly simplified this after a discussion with Quincey.

• Cleanup threadlocal error stack at individual thread exit time
• Rename H5E__clear_stack() to H5E__destroy_stack() to contrast its intention with H5E_clear_stack()
• Add a ttsafe test

[qkoziol]

Small change, otherwise good :-)