* gnu/packages/patches/eigen-arm-neon-fixes.patch: New patch.
* gnu/packages/algebra.scm (eigen): Update to 3.3.4.
[source]: Use patch. Disable svd-preallocation test for BDCSVD.
[arguments]: Set "EIGEN_SEED" environment variable in check phase.
* gnu/local.mk (dist_patch_DATA): Add patch.