travis: switched from gox to GOOS/GOARCH environment variables for build tests on supported platforms

.travis.yml

@@ -3,14 +3,13 @@ language: go
 go:
   - 1.6
 
-before_install:
-  - go get github.com/mitchellh/gox
-
 script:
   # build test for supported platforms
-  - gox -os="linux"
-  - gox -os="darwin"
-  - gox -os="freebsd"
+  - GOOS=linux go build
+  - GOOS=darwin go build
+  - GOOS=freebsd go build
+  - GOOS=windows go build
+  - GOARCH=386 go build
 
   # run tests on a standard platform
   - go test -v ./...