Enable bdcsvd on host.

Currently if compiled by NVCC, the `MatrixBase::bdcSvd()` implementation
is skipped, leading to a linker error.  This prevents it from running on
the host as well.

Seems it was disabled 6 years ago (5384e891) to match `jacobiSvd`, but
`jacobiSvd` is now enabled on host.  Tested and runs fine on host, but
will not compile/run for device (though it's not labelled as a device
function, so this should be fine).

Fixes #2139

Eigen/src/SVD/BDCSVD.h

@@ -1330,7 +1330,6 @@ void BDCSVD<MatrixType>::deflation(Eigen::Index firstCol, Eigen::Index lastCol,
 #endif
 }//end deflation
 
-#if !defined(EIGEN_GPUCC)
 /** \svd_module
   *
   * \return the singular value decomposition of \c *this computed by Divide & Conquer algorithm
@@ -1343,7 +1342,6 @@ MatrixBase<Derived>::bdcSvd(unsigned int computationOptions) const
 {
   return BDCSVD<PlainObject>(*this, computationOptions);
 }
-#endif
 
 } // end namespace Eigen