pi zero w support

[olliephillips]

Noted that unless I build with GOARM=6 the compiled binary will not run on pi zero w, it outputs "Illegal Instruction". Happy to amend README, since I think other newcomers might find the same, and be deterred.

I have LED0 blinking, but should I expect embd library to work on pi zero w with existing Rasp Pi board definition files?

[danesparza]

Hmmm ... what version of Go are you using? With Go 1.8, I just needed to export GOOS=linux and
export GOARCH=arm in order to build the correct arm binary on Windows (that I then SCP'd to my Raspberry Pi Zero W).

[olliephillips]

I'm cross compiling from a Mac on Go 1.8

It's like it is using GOARM=7 by default, since if I use 7 I also get same error as if GOARM env var omitted.

pi@pizero3:~ $ sudo ./simpleblinker
Illegal instruction

So I need to explicitly set GOARM=6 for it to work.