[Buildroot] Reduce toolchain options

[Gustavo Zacarias]

On 03/11/2015 01:28 PM, Peter Korsgaard wrote:

> Yes, I agree.
> 
> I'm also somewhat scared of forcing IPv6 support but perhaps it will be
> safe, people using !uClibc have probably noticed these issues already.

I've found one downside of dropping non-IPv6: the codesourcery SH2A
toolchains lack IPv6 support :-(
We can still kill the LFS option though.
Regards.