Use jemalloc for aligned allocation

[xhochy]

This also fixes the OSX build (cc @MarcAntoineSchmidtQC ) and should also improve on allocation times).

Depends on conda-forge/jemalloc-feedstock#18

[tbenthompson]

Looks good to me as long as the CI tests pass. One comment, but I don't think it's necessary to do anything if you don't want to.

[tbenthompson]

Looks like the build is failing with

/opt/conda/bin/../lib/gcc/x86_64-conda-linux-gnu/7.5.0/../../../../x86_64-conda-linux-gnu/bin/ld: cannot find -lquadmath

during the installation of glmnet_python.

That doesn't seem related to any of the changes you made. But I'm pretty sure we pinned to a specific glmnet_python commit so I'm confused why you're getting that error.

[xhochy]

The CI failure could be related to conda-forge/ctng-compilers-feedstock#23

[MarcAntoineSchmidtQC]

Just want to point out that this doesn't work for me right now. gxx_impl_linux-64=7.5.0=*_6 and gfortran_impl_linux-64=7.5.0=*_6 are, as the name suggest, linux-only packages. No worries if this is still a work in progress.

[xhochy]

Just want to point out that this doesn't work for me right now. gxx_impl_linux-64=7.5.0=*_6 and gfortran_impl_linux-64=7.5.0=*_6 are, as the name suggest, linux-only packages. No worries if this is still a work in progress.

They were just temporarily added to fix the CI. You don't need them on OSX.

[xhochy]

Next jemalloc packaging issue: conda-forge/jemalloc-feedstock#19

[tbenthompson]

Looks great! Thanks Uwe!