The asserted order of THREAD_DESTROY and end of main() is not
guaranteed:
```
7: Hello from pthread
8: THREAD_TERMINATE 0x7e8000104000, self: 0x7e8000104000, name: child thread
9: Done.
10: THREAD_DESTROY 0x7e8000104000, self: 0x7e8000104000, name: child thread
```
Resulting in:
```
error: CHECK: expected string not found in input
// CHECK: Done.
```
Remove checking for "Done." (end of main()) to deflake this test.
Alternatively, we could use `CHECK-DAG`.
rdar://94036145
Thread create/destroy events are not guaranteed to belivered on the
parent thread, e.g., output from a CI job:
```
5: THREAD_CREATE 0x7e8000104000, self: 0x1102ebdc0, name: n/a
6: THREAD_START 0x7e8000104000, self: 0x7e8000104000, name: n/a
7: Hello from pthread
8: THREAD_TERMINATE 0x7e8000104000, self: 0x7e8000104000, name: child thread
9: THREAD_DESTROY 0x7e8000104000, self: 0x7e8000104000, name: child thread
```
Here, THREAD_DESTROY is delivered on the thread being destroyed.
rdar://92679941
Add integration tests for dyld interposition: DYLD_LIBRARY_PATH and
DYLD_INSERT_LIBRARIES.
DYLD_INSERT_LIBRARIES is also relevant for TSan thread
finalization/destruction sequence in the presence of additional pthread
introspection hooks (libBacktraceRecording.dylib for Xcode 'Queue
Debugging' feature).
rdar://78739125
Differential Revision: https://reviews.llvm.org/D109332
Julian Lettner