Travis: use Android docker image for build

This should make it easier to make changes to our build environment.

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

scripts/android/before_install.sh

@@ -6,14 +6,16 @@ git fetch --unshallow
 git pull --tags
 git describe
 
-# Ugly, but keeps it running during the build
-docker run -v $PWD:/workspace/subsurface --name=builder -w /workspace -d ubuntu:bionic /bin/sleep 60m
-docker exec -t builder apt-get update
-# subsurface android build dependencies
-docker exec -t builder apt-get install -y git cmake autoconf libtool-bin openjdk-8-jdk-headless wget unzip python bzip2 pkg-config
-# Qt installer dependencies
-docker exec -t builder apt-get install -y libx11-xcb1 libgl1-mesa-glx libglib2.0-0
-# Inject cached 3pp's (if none exists in 3pp dir, we inject zero ones, and all is downloaded in the container)
-# TODO: caching
-#docker cp 3pp builder:/workspace
-docker exec -t builder mkdir -p /workspace/3pp
+# setup build dir on the host, not inside of the container
+mkdir -p ../subsurface-mobile-build-arm
+
+# this uses a custom built Ubuntu image that includes Qt for Android and
+# Android NDK/SDK
+# Running sleep to keep the container running during the build
+PARENT="$( cd .. && pwd )"
+docker run -v $PWD:/android/subsurface \
+	   -v $PARENT/subsurface-mobile-build-arm:/android/subsurface-mobile-build-arm \
+	   --name=builder \
+	   -w /android \
+	   -d dirkhh/android-builder:5.11.03 \
+	   /bin/sleep 60m