Travis: add Qt 5.6 testing

This is done via OpenSUSE Leap/42.3 which seemed the easiest way to
get a 5.6 based distro.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

.travis.yml

@@ -112,7 +112,13 @@ matrix:
 #              - 3pp
 
     - env: SUBSURFACE_PLATFORM="qt55"
-      # Currently hard coded to arm
+      os: linux
+      language: c++
+      filter_secrets: false
+      services:
+          - docker
+
+    - env: SUBSURFACE_PLATFORM="qt56"
       os: linux
       language: c++
       filter_secrets: false

scripts/qt56/after_success.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo "Build with Qt 5.6 succeeded"

scripts/qt56/before_install.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+# Travis only pulls shallow repos. But that messes with git describe.
+# Sorry Travis, fetching the whole thing and the tags as well...
+git fetch --unshallow
+git pull --tags
+git describe
+
+# Ugly, but keeps it running during the build
+docker run -v $PWD:/workspace/subsurface --name=builder -w /workspace -d opensuse:42.3 /bin/sleep 60m
+
+# Subsurface build dependencies
+docker exec -t builder zypper refresh
+docker exec -t builder zypper --non-interactive install \
+	git gcc-c++ make autoconf automake libtool cmake libzip-devel \
+	libssh2-devel libxml2-devel libxslt-devel sqlite3-devel libusb-1_0-devel \
+	libqt5-linguist-devel libqt5-qttools-devel libQt5WebKitWidgets-devel \
+	libqt5-qtbase-devel libQt5WebKit5-devel libqt5-qtsvg-devel \
+	libqt5-qtscript-devel libqt5-qtdeclarative-devel \
+	libqt5-qtconnectivity-devel libqt5-qtlocation-devel libcurl-devel

scripts/qt56/travisbuild.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+set -x
+set -e
+
+docker exec -t builder subsurface/scripts/build.sh -desktop 2>&1 | tee build.log
+# fail the build if we didn't create the target binary
+grep /workspace/install-root/bin/subsurface build.log
+