WIP, BLD: add ppc64le, aarch64, s390x builds

Author: mattip

.travis.yml

@@ -21,15 +21,37 @@ services: docker
 matrix:
   include:
     - os: linux
+        - LABEL=64bit-linux
     - os: linux
       env:
+        - LABEL=32bit-linux
         - PLAT=i686
     - os: osx
       language: objective-c
+        - LABEL=64bit-macOS
     - os: osx
       language: objective-c
       env:
+        - LABEL=32bit-macOS
         - PLAT=i686
+    - os: linux
+      arch: arm64
+      env:
+        - LABEL=64bit-aarch64
+        - PLAT=aarch64
+        - MB_ML_VER=2014
+    - os: linux
+      arch: s390x
+      env:
+        - LABEL=64bit-s390x
+        - MB_ML_VER=2014
+        - PLAT=s390x
+    - os: linux
+      arch: ppc64le
+      env:
+        - LABEL=64bit-ppc64le
+        - MB_ML_VER=2014
+        - PLAT=ppc64le
 
 before_install:
     - source travis-ci/build_steps.sh