[OS] CBC and threads

[Mike Steglich]

We found an interesting Cbc behavior under several linux systems. If the parameter threads is assigned a wrong value (e.g. greater than the available cores) then crashes the Cbc binary (and also OSSolverService when Cbc is used). The problem appears under Linux with Cbc 2.7 and also 2.8  but not on diverse Macs.  (I didn't  test it under Windows). 

Cheers,

Mike Steglich