How to set locale in Makefile? wip/elixir not recognising UTF-8

[atomicules <base%atomicules.co.uk@localhost>]

Hey all,

In wip/elixir when it builds I get these error messages:

```
warning: the VM is running with native name encoding of latin1 which 
may cause Elixir to malfunction as it expects utf8. Please ensure your 
locale is set to UTF-8 (which can be verified by running "locale" in 
your shell)
```

If I run `gmake` outside of pkgsrc then it picks up the locale from 
my shell/environment and works fine. But there's something about doing 
a pkgsrc build that makes the above error/warning occur.

I've tried setting the following in the Makefile:

```
MAKE_ENV += LC_CTYPE="en_US.UTF-8"
MAKE_ENV += LC_LANG="en_US.UTF-8"
MAKE_ENV += LC_ALL=""
```

But to no avail. I've done a lot of searching, but am stumped on this 
one. Anyone got any ideas?