Add linux/386 testing back to Travis

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

.travis.yml

@@ -7,13 +7,12 @@ sudo: false
 env:
     - TRAVIS_GLOBAL_WTF=1
     - _GOOS=linux _GOARCH=amd64
-#    - _GOOS=linux _GOARCH=386 # Travis can't currently do 32bit cgo... (see https://travis-ci.org/tianon/libcontainer/jobs/30126518#L168)
+    - _GOOS=linux _GOARCH=386 # CGO_ENABLED=1 # TODO add this once Travis can handle it (ie, has the headers and stuff we need - see https://travis-ci.org/tianon/libcontainer/jobs/30126518#L167 "pkg/runtime/cgo/cgo.go:26:46: fatal error: sys/types.h: No such file or directory")
 #    - _GOOS=linux _GOARCH=arm # see https://github.com/moovweb/gvm/issues/22
 
 install:
     - mkdir -pv "${GOPATH%%:*}/src/github.com/docker" && [ -d "${GOPATH%%:*}/src/github.com/docker/libcontainer" ] || ln -sv "$(readlink -f .)" "${GOPATH%%:*}/src/github.com/docker/libcontainer"
     - if [ -z "$TRAVIS_GLOBAL_WTF" ]; then
-          export CGO_ENABLED=1;
           gvm cross "$_GOOS" "$_GOARCH";
           export GOOS="$_GOOS" GOARCH="$_GOARCH";
       fi