Circle3D: fix optimizeModelCoefficients use an uninitialized var

[sunbuny]

pcl::SampleConsensusModelCircle3D::optimizeModelCoefficients use a uninitialized var as a initial guess to do the minimization. It will never get a correct answer, and the minimization will never be done. This PR fix it.

[mvieth]

Thanks for fixing this! I think the last three coefficients, that represent the normal direction, also need to be normalized after the minimization, like so: coeff.tail<3>().normalize();. Could you add that as well, please?

[sunbuny]

Thanks for fixing this! I think the last three coefficients, that represent the normal direction, also need to be normalized after the minimization, like so: coeff.tail<3>().normalize();. Could you add that as well, please?

You are right， the axis is not nomalized after the minimization. This will not affect the result, but will confuse the user.

[mvieth]

Thanks!