Check CPUIDs to get placement / core count information

[markusbattarbee]

To extend #1053, we could check how many unique CPUIDs are on each node. This would allow logging as core-hours instead of thread-hours.

https://stackoverflow.com/questions/1666093/cpuid-implementations-in-c

This would also be helpful in printing to the logfile straight away how many cores are actually in use, so that if we have bad placement, it would be evident.