Add Windows build config to Travis

.travis.yml

@@ -2,7 +2,8 @@ language: go
 sudo: false
 dist: trusty
 env:
-  HUGO_BUILD_TAGS="extended"
+  global:
+  - HUGO_BUILD_TAGS="extended"
 git:
   depth: false
 go:
@@ -11,23 +12,33 @@ go:
 os:
   - linux
   - osx
+  - windows
 matrix:
   allow_failures:
     - go: tip
   fast_finish: true
+  exclude:
+  - os: windows
+    go: tip
+
 install:
   - mkdir -p $HOME/src
   - mv $HOME/gopath/src/github.com/gohugoio/hugo $HOME/src
   - export TRAVIS_BUILD_DIR=$HOME/src/hugo
   - cd $HOME/src/hugo
   - go get github.com/magefile/mage
 script:
-- go mod download
-- mage -v test
-- mage -v check
-- mage -v hugo
-- ./hugo -s docs/
-- ./hugo --renderToMemory -s docs/
+  - go mod download
+  - mage -v test
+  - mage -v check
+  - mage -v hugo
+  - ./hugo -s docs/
+  - ./hugo --renderToMemory -s docs/
+  - df -h
+
 before_install:
+  - df -h
+    # https://travis-ci.community/t/go-cant-find-gcc-with-go1-11-1-on-windows/293/5
+  - if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then choco install mingw -y; export PATH=/c/tools/mingw64/bin:"$PATH"; fi
   - gem install asciidoctor
   - type asciidoctor