Remove potentially extraneous generation of regions

[zvonimir]

While working on pull request #508, I realized that the following if condition that leads to regions being generated is maybe not needed https://github.com/smackers/smack/blob/691b231dfd6ffc00924c533164c31a6596d3b84c/lib/smack/Regions.cpp#L350-L351

The only theory I have for why we would need it here is that it is somehow related to the processing of __SMACK_values functions. But if that is indeed the case, then it should be guarded by their names.