Fix in ECM to avoid "illegal instruction "at the launch of ECM-4.0.

The first issue is related to the execution of ECM-4.0 on pretty old linux machines (having Westmere Intel architecture). Despite the ECM4.0 source code can be successfully compiled on these machines, the executable code immediately generates an “illegal instruction” at the launch. When debugging, the “illegal instruction” is related to some recent modifications introduced by the contribution Y0141 (Sign prediction improvement) and is related to the initialization of some “static const” variables with intrinsic commands.