travis: Add s390

Presubmit: https://travis-ci.com/nathanchance/continuous-integration/builds/147875953

[skip ci]

Signed-off-by: Nathan Chancellor <[email protected]>

Author: nathanchance

.travis.yml

@@ -18,6 +18,8 @@ jobs:
       env: ARCH=ppc64
     - name: "ARCH=ppc64le LD=ld.lld"
       env: ARCH=ppc64le LD=ld.lld-11
+    - name: "ARCH=s390"
+      env: ARCH=s390
     - name: "ARCH=x86_64 LD=ld.lld"
       env: ARCH=x86_64 LD=ld.lld-11
     # linux (cron only)
@@ -47,6 +49,9 @@ jobs:
     - name: "ARCH=ppc64le LD=ld.lld REPO=linux-next"
       env: ARCH=ppc64le LD=ld.lld-11 REPO=linux-next
       if: type = cron
+    - name: "ARCH=s390 REPO=linux-next"
+      env: ARCH=s390 REPO=linux-next
+      if: type = cron
     - name: "ARCH=x86_64 LD=ld.lld REPO=linux-next"
       env: ARCH=x86_64 LD=ld.lld-11 REPO=linux-next
       if: type = cron