NEURON tests fail when splay tree queueing is disabled in CoreNEURON

[olupton]

Describe the issue
If CoreNEURON is configured with CORENRN_ENABLE_SPLAYTREE_QUEUING=OFF, the following NEURON tests segfault:

         46 - coreneuron_modtests::test_netmove_py_cpu (Failed)
         54 - coreneuron_modtests::inputpresyn_py_cpu (Failed)
         63 - coreneuron_modtests::test_netmove_py_gpu (Failed)
         71 - coreneuron_modtests::inputpresyn_py_gpu (Failed)
        185 - tqperf::coreneuron (Failed)

Expected behavior
Either the failures should be fixed, or these tests should be disabled when this option is set (with a reference to this issue).

Additional context

CoreNeuron/CMakeLists.txt

Lines 351 to 354 in 511613e

	# splay tree required for net_move
	if(CORENRN_ENABLE_SPLAYTREE_QUEUING)
	add_definitions("-DENABLE_SPLAYTREE_QUEUING")
	endif()

suggests this is a known (to some people!) issue, but I didn't see a ticket for it.