Changes applied in commit 4fabde349f16b59f37568da2a4c050c6dd53a34e broke VxWorks tests and examples, many of which crash with error: ``` pthreadLib: unable to create POSIX thread internal attributes. ``` This error appeared in multiple tests, but was tested on tst_QSignalSpy, where it was 100% reproducible (I haven't check other tests for reproducibility). This above error is printed when VxWorks task starts and initializes its pthread containers. Pthread starting procedure results in error `S_objLib_OBJ_ID_ERROR`, on which documentation states that it means "The <tid> parameter is an invalid task ID". This happens because VxWorks pthread implementation clears its internal data, and only then passes control to `taskExit` system procedure, which calls thread_local destructors. Any calls to `pthread` routines which require current thread internal data ends with error and termination. While VxWorks uses clang internally, it implements `__cxa_thread_atexit` and `__cxa_thread_atexit_impl`, which makes it pass `TEST_cxa_atexit` in CMake, even thou their call order is different than on other platforms. Enable QT_FEATURE_broken_threadlocal_dtors for VxWorks by failing compilation of cxa_thread_atexit* tests, which fixes the crashes on VxWorks. Task-number: QTBUG-115777 Change-Id: I4109b66903333a94301afe7fe5634ac4365a70b4 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>