Apple M1 does not compile with -DNRN_ENABLE_TESTS=ON

[nrnhines]

Experience the same compile problem with catch2 mentioned in BlueBrain/nmodl#529.

The fix from BlueBrain/nmodl#528 also fixes our compile problem for external/catch2/single_include/catch2/catch.hpp .

But see test failures 4-18. Note that 7 onward are for testcorenrn... which is odd because we did not use the -DNRN_ENABLE_CORENEURON=ON option

[nrnhines]

Although make test fails for 4-18 manual testing succeeds for Test 4 with

cd test/pynrn
nrnivmodl
python3 -m pytest

Test 5: Doing this for test/rxd (nrnivmodl in ecs and 3d) succeeds for test_contains, test_currents, test_distance, but segfaults for test_empty_regions

Test 6: test/parallel_test was successful with mpiexec -n 6 nrniv -mpi -python test_subworld.py but I needed a
export DYLD_LIBRARY_PATH=/opt/homebrew/lib

[pramodk]

@nrnhines : got access to Apple M1 and hence started testing with NMODL. Will do the same for CoreNEURON and NEURON on Monday.