stub syscall.Environ and syscall. SysProcAttr so stdlib tests using internal/testenv can build

[dgryski]

No description provided.

[dgryski]

Actually, it's not clear this is necessarily the lowest hanging fruit to get more stdlib tests passing out of the box. Might be worth poking around to a bit to what the easiest way forward is.

[aykevl]

I think implementing syscall.Environ wouldn't be very difficult (see syscall.Getenv for example), so I would prefer if it was fully implemented from the start.

[dgryski]

Building our own internal/testenv might make more sense. It's a pretty small package that we can easily tailor to testing needs. However, since many of the tests look for particular features and then call t.Skip() (which isn't yet supported), the runtime behaviour of the tests may not be what we expect if even they can now build.

[dkegel-fastly]

This would help github.com/getlantern/golog build. (Along with go-stack/stack#31.)

Given that I ran into it really quickly in my little fishing expedition, this seems high value.

[dgryski]

This was handled in #2268

@dkegel-fastly If you're still having trouble with getlantern/golog or go-stack/stack, let's open new bugs with what's actually missing.