Elixir checker accept optional environment

[tsubery]

The solution proposed here wasn't working for. elixirc reported errors on many files that mix wasn't. It must have something to do with build environments.

With this patch we can set let g:syntastic_elixir_compile_env = { 'MIX_ENV': 'test' } and
workaround this issue by building in a different environment.

[lcd047]

The elixir checker is already broken beyond fixing, mainly because error messages produced by Elixir are way too hard to parse with errorformat. So this checker is pretty high on the list of things to remove in a future release of syntastic.

In the mean time, you could achieve what you want without changes to the code, by using a script wrapper that sets whatever environment variables you want. Thus, sorry, but no.