fix un-threadsafe code for creating config enum hashtable.

[supermerill]

Hello

Someone had a random bug.
I tracked it to the initialisation of the config enum.
Some of them are thread-safe and some don't, so I put all of them to be thread-safe.
Same for the serialize() that wasn't thread-safe (imo).

I hope I didn't add a typo in the last edit.

[bubnikv]

Thanks for pointing that out. It may have been a problem. Fixed with a7368b9.

The static tables are now initialized statically. Comparing to a static variable inside a function, static variable outside of a function does not require the compiler generated synchronization primitive (which is a bit costly because it flushes write caches on Intel CPUs every time the function is visited), however order of initialization of static variables is not defined between compilation units.

Also the get_enum_names() are statically generated as well.