Update Eigen to commit:3bb6a48d8c171cf20b5f8e48bfb4e424fbd4f79e

CHANGELOG
=========
3bb6a48d8 - Fix bug atan2
14c847dc0 - Refactor special values test for pow, and add a similar test for atan2
462758e8a - Don'\''t use generic sign function for sign(complex) unless it is vectorizable
c0d6a7261 - Use pnegate(pzero(x)) as a generic way to generate -0.0. Some compiler do not handle the literal -0.0 properly in fastmath mode.
7846c7387 - Eigen/Sparse: fix warnings -Wunused-but-set-variable
316754487 - Handle NaN inputs to atan2.
72db3f0fa - Remove references to M_PI_2 and M_PI_4.
d6bc06259 - Remove reference to EIGEN_HAS_CXX11_MATH.
5ceed0d57 - Guard GCC-specific pragmas with "#ifdef EIGEN_COMP_GNUC"
528b68674 - [clang-format] Add a few macros to AttributeMacros
e95c4a837 - Simpler range reduction strategy for atan<float>().
80efbfded - Unconditionally enable CXX11 math.
e5794873c - Replace assert with eigen_assert.
7d6a9925c - Fix 4x4 inverse when compiling with -Ofast.
1414a76fa - Only vectorize atan<double> for Altivec if VSX is available.
c475228b2 - Vectorize atan() for double.
1e1848fdb - Add a vectorized implementation of atan2 to Eigen.

* Switch TensorFlow to using the new fast atan2 in Eigen.
* Get rid of local implementations since Eigen is now guaranteed to support C++11 math.

PiperOrigin-RevId: 481044760
Change-Id: Ibb2e835abae11d2dac14b811af7b7b3b766a1672
42 files changed