Autotuner doesn't account for all spawning functions

[sim642]

Currently the autotuner looks for any special function of the ThreadCreate kind to determine if multi-threaded analysis is needed or not.
As pointed out in #1174 (comment), this check is insufficient because we have other library function specification whose arguments we spawn to perform a sound analysis.

Therefore, the autotuner should instead look for library functions whose arguments contain spawning accesses.