circuit example fails with tracing + -lg:dump_physical_traces

[rohany]

Edit the circuit example (examples/circuit/circuit.cc) to use tracing, and run with -lg:dump_physical_traces -level tracing=2. This error will be reported:

[0 - 700001f5c000]    1.823599 {5}{runtime}: LEGION ERROR: Unable to find entry for region tree ID 1 (from file /Users/rohany/Documents/research/legion/runtime/legion/region_tree.cc:4401)

[lightsighter]

It's clear to me why this is happening, but it's not an easy thing to fix at the moment. I have a change I'm planning to make later this year that will address it but need to hold off doing that for now. If necessary we can find a hack that works around it sooner.