Add support for GO15VENDOREXPERIMENT

[janeczku]

Add support for GO15VENDOREXPERIMENT

[karalabe]

I'll add a flag to allow passing arbitrary environmental variables. Though I'm across the continent on a conference so will only be able to address this next week.

[bryanl]

@karalabe is this still something you are planning?

[karalabe]

Dunno really, the vendor experiment flag is enabled by default on Go 1.6, so you can already use it by default with --go=1.6beta1. As the final Go 1.6 release should be done anyway in a month or so, I think there's not much benefit in complicating things with this experimental flag. Any great need for it that cannot be done with Go 1.6 (beta for now)?

[karalabe]

Closing as xgo already uses Go 1.6, featuring this.