ADIOS BP5 Support: Conditional Compile Variant

[ax3l]

Unfortunately, we cannot rely on ADIOS 2.8.0+ to provide BP5 unconditionally.

https://github.com/ornladios/ADIOS2/blob/v2.8.0/CMakeLists.txt#L155

We need to do more checks if that compile option was actually set.

X-ref: ornladios/ADIOS2#3182