Bug#863507: numba: test collection crashes/errors out [armel, ppc64el]

[Rebecca N. Palmer]

Control: retitle -1 test collection crashes/errors out [armel, ppc64el]

The tests now do get run on armhf, but still don't on armel and ppc64el. 
  This appears to be because some test modules crash/abruptly exit 
*during test collection*.  (pytest-xdist can start a new worker after a 
crash, but each worker collects all tests before running any of them, so 
if collection crashes no tests ever get run.)

The files affected are
ppc64el and armel: test_typedlist.py

armel only:
test_errorhandling.py
test_inlining.py
test_serialize.py
npyufunc/test_ufuncbuilding.py

The exact errors aren't displayed from pytest, but are if one imports 
these modules directly.  They suggest that the armel crash might be 
related to #863508 (it no longer happens during documentation build, but 
might not be totally fixed) and the ppc64el one to 
https://github.com/numba/numba/issues/4026

qemu-armel$ python3 -X faulthandler ; echo $?
Python 3.8.3 (default, May 14 2020, 11:03:12)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
 >>> import numba.tests.test_typedlist
LLVM ERROR: Symbol not found: __sync_fetch_and_add_4
1

(If you want to set a breakpoint here, it's probably 
https://sources.debian.org/src/llvm-toolchain-8/1:8.0.1-9/lib/Support/ErrorHandling.cpp/?hl=126#L115 
)

qemu-ppc64el$ python3 -X faulthandler
Python 3.8.3 (default, May 14 2020, 11:03:12)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
 >>> import numba.tests.test_typedlist
/usr/lib/python3/dist-packages/numpy/core/getlimits.py:53: 
RuntimeWarning: divide by zero encountered in log10
   self.precision = int(-log10(self.eps))
Fatal Python error: Segmentation fault

Current thread 0x0000004000d5ed20 (most recent call first):
   File "/usr/lib/python3/dist-packages/numba/typed/typedlist.py", line 
260 in append
   File "/usr/lib/python3/dist-packages/numba/tests/test_typedlist.py", 
line 25 in <module>
   File "<frozen importlib._bootstrap>", line 219 in 
_call_with_frames_removed
   File "<frozen importlib._bootstrap_external>", line 783 in exec_module
   File "<frozen importlib._bootstrap>", line 671 in _load_unlocked
   File "<frozen importlib._bootstrap>", line 975 in _find_and_load_unlocked
   File "<frozen importlib._bootstrap>", line 991 in _find_and_load
   File "<stdin>", line 1 in <module>
qemu: uncaught target signal 11 (Segmentation fault) - core dumped
Segmentation fault

The above testing was with 0.48.0-5 (unstable), but the build logs imply 
that this bug still exists in 0.49.1-1exp1 (experimental).