add full cross compilation in travis (sirupsen#963)

* add full cross compilation in travis

* reduce the travis build matrix

* disable cross build for plan9 and nacl

.travis.yml

@@ -6,11 +6,19 @@ env:
   - GO111MODULE=on
   - GO111MODULE=off
 go: [ 1.11.x, 1.12.x ]
-os: [ linux, osx, windows ]
+os: [ linux, osx ]
+matrix:
+  exclude:
+    - go: 1.12.x
+      env: GO111MODULE=off
+    - go: 1.11.x
+      os: osx
 install:
+  - ./travis/install.sh
   - if [[ "$GO111MODULE" ==  "on" ]]; then go mod download; fi
   - if [[ "$GO111MODULE" == "off" ]]; then go get github.com/stretchr/testify/assert golang.org/x/sys/unix github.com/konsorten/go-windows-terminal-sequences; fi
 script:
+  - ./travis/cross_build.sh
   - export GOMAXPROCS=4
   - export GORACE=halt_on_error=1
   - go test -race -v ./...

travis/cross_build.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+if [[ "$TRAVIS_GO_VERSION" =~ ^1.\12\. ]] && [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
+    /tmp/gox/gox -build-lib -all -os '!plan9 !nacl'
+fi

travis/install.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -e
+
+if [[ "$TRAVIS_GO_VERSION" =~ ^1.\12\. ]] && [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
+    git clone https://github.com/dgsb/gox.git /tmp/gox
+    pushd /tmp/gox
+    git checkout new_master
+    go build ./
+    popd
+fi