Presumably wrong value of `PI` constant

[cadaniluk]

In libff, both common/double.cpp and algebra/fields/field_utils.tcc define the constant PI as

const double PI = 3.141592653589793238460264338328L;

But isn't the 0 wrong? As this website says, for example, it is (rounded)

3.14159265358979323846264338328