Add cross compilation (#127)

* Add cross compilation

Add 386 as 32 bit test, arm64 and ppc64le since they have assembly.

.travis.yml

@@ -27,6 +27,9 @@ script:
  - go build examples/stream-decoder.go
  - go build examples/stream-encoder.go
  - diff <(gofmt -d .) <("")
+ - GOARCH=386 GOOS=linux go build .
+ - GOARCH=arm64 GOOS=linux go build .
+ - GOARCH=ppc64le GOOS=linux go build .
 
 matrix:
   allow_failures:

galoisAvx512_amd64.go

@@ -229,7 +229,7 @@ func (r reedSolomon) codeSomeShardsAvx512P(matrixRows, inputs, outputs [][]byte,
 	if do < r.o.minSplitSize {
 		do = r.o.minSplitSize
 	}
-	// Make sizes divisible by 32
+	// Make sizes divisible by 64
 	do = (do + 63) & (^63)
 	start := 0
 	for start < byteCount {