bump compiler for linux-aarch64 to 11

[esc]

Numba team build system for linux-aarch64 is being updated from Miniforge3 to miniconda3 based docker containers. llvmlite fails to compile from main with current recipe specification as compiler version 9 is not available for that architecture. We bump to 11 which is the default as referenced by:

https://github.com/AnacondaRecipes/aggregate/blob/master/conda_build_config.yaml

For reference, the error was:

The following packages are incompatible
├─ gcc_linux-aarch64 9.*  does not exist (perhaps a typo or a missing channel);
└─ gxx_linux-aarch64 9.*  does not exist (perhaps a typo or a missing channel).

[gmarkall]

Why do we use 7 for Linux on non-AArch64? I see the comment in conda_build_config.yaml says:

Numba/llvmlite stack needs an older compiler for backwards compatability.

but if we can bump to 11 on AArch64, does that mean that the above comment is no longer relevant?

[esc]

Why do we use 7 for Linux on non-AArch64? I see the comment in conda_build_config.yaml says:

Numba/llvmlite stack needs an older compiler for backwards compatability.

but if we can bump to 11 on AArch64, does that mean that the above comment is no longer relevant?

I did wonder about that too, I looked at the Anaconda feedstock here:

https://github.com/AnacondaRecipes/llvmlite-feedstock/tree/master/recipe

and it seems like they did away withe the cbc file altogether...

[esc]

Also, we can not compile llvmlite with only the change to cbc file. It turns out that the llvmdev that we use was also built with Miniforge3 compilers. Running this PR as is with just b09b4cd results in:

- The following package could not be installed
- └─ llvmdev 15.*  is not installable because it requires
- └─ libgcc-ng >=12 , which does not exist (perhaps a missing channel).

😢

[esc]

llvmdev has been fresh build 2 variants on anaconda.org under both numba/label/main and numba/label/ci (except for ppc64le for which no new continuumio/miniconda3 contains are available because that platform is no longer supported (last release for `ppc64le1 was https://hub.docker.com/layers/continuumio/miniconda3/23.10.0-1/images/sha256-166ff37fba6c25fcad8516aa5481a2a8dfde11370f81b245c1e2e8002e68bcce?context=explore)

[esc]

With the build 2 variant this PR passes all the llvmlite tests on the Anaconda build farm!