conformance/interfaces/pthread_create/10-1.c is broken in several ways.

Firstly, relies on uninitialized stack data to create a (hopefully-invalid and crash-causing pthread_attr_t:

https://github.com/emscripten-core/posixtestsuite/blob/869e266b090a8d44e51bb040904c942556b1e4ab/conformance/interfaces/pthread_create/10-1.c#L97

Secondly it calls pthread_exit() with an error code from a signal handler installed on the main thread:

https://github.com/emscripten-core/posixtestsuite/blob/869e266b090a8d44e51bb040904c942556b1e4ab/conformance/interfaces/pthread_create/10-1.c#L89

The author seems to think that calling pthead_exit() like this will cause the overall test to return the error code, but that is now how it works. Calling pthead_exit form the main thread always exist with code 0.. the value passed to pthread_exit is *only* used when the thread is being joined.. not when exiting the process. This means the test will print that it failed `Test FAILED: Did not receive segmentation fault signal, waited 10 seconds` but actually return zero as the process exit code.