This is to make it consistent with an upcoming addition of VIRCADIA_THREAD_DEBUGGING.
Also, check if the variable contains anything and isn't just defined to avoid hard
to figure out bugs and confusion.
It seems that libasan was running into some sort of trouble due to static linking.
Additionally, -fstack-protector-strong has been enabled by disabling the usage of
the FIR_1x4_AVX512 function under memory debugging.