travis: set up running tests on Travis CI

.travis.yml

@@ -0,0 +1,27 @@
+sudo: required
+dist: trusty
+language: minimal
+env:
+  matrix:
+    - ARCH=x86_64
+    - ARCH=x86
+    - ARCH=aarch64
+    - ARCH=armhf
+    - ARCH=ppc64le
+before_install:
+  - "wget 'https://raw.githubusercontent.com/alpinelinux/alpine-chroot-install/v0.5.0/alpine-chroot-install' \
+        && echo '1866bc078cab859cefcbdbbd2dee0141e0bee8d5  alpine-chroot-install' | sha1sum -c || exit 1"
+  - alpine() { /alpine/enter-chroot -u "$USER" "$@"; }
+install:
+  - sudo sh alpine-chroot-install -a "$ARCH"
+        -p 'build-base alpine-sdk libfetch-dev libressl libressl-dev linux-headers lua5.2-dev zlib-dev'
+before_script:
+  - /alpine/enter-chroot "addgroup $USER wheel && addgroup $USER abuild"
+  - alpine abuild-keygen -ain
+script:
+  - alpine make
+  - alpine src/apk --version
+  - alpine make static
+  - alpine src/apk.static --version
+  - alpine make check
+  - alpine make -C test root-tests