fix unthread safe memory allocation

[i-kanamori]

Hi Matthias,

I found an unthread safe memory allocation in
void interpolation_PRECISION_define( ... ) in setup_generic.c,
which sometimes caused segmentation faults in my environment. Depending on the timing, any thread/core can overwrite buffer[0] with NULL after the master allocated the memory to buffer[0].
Could you have a look at my change? I wander other users might be suffering from the same problem.
Thanks a lot!

Issaku

[DDalphaAMG]

Dear Issaku,

thanks a lot for reporting this issue, I hopefully fixed it. Please let me know in case that you encounter further problems.

Best wishes
Matthias