cx.ring: update to VC 95

* remove some legacy build commands
* we need swig from backports otherwise building the cx.ring.daemon
silently fails and the build of the java part breaks.
* update maintainer notes

closes #808

metadata/cx.ring.txt

@@ -463,11 +463,28 @@ Build:20170531,79
         ./compile.sh release
     ndk=r14b
 
-Maintainer Notes:
-Looks like buildserver/setup-env-vars wasnt properly run the last time. PATH
-should in fact already includee /opt/gradle:
+Build:20171020,95
+    commit=39ad60848d702bfdd3dd9ac89a493c51ce5c9ab0
+    subdir=client-android/ring-android/app
+    submodules=yes
+    sudo=apt-get update && \
+        apt-get install --yes -t jessie-backports swig
+    output=build/outputs/apk/app-release-unsigned.apk
+    scandelete=client-windows,client-uwp
+    build=echo -e '#!/bin/sh\ngradle "$@"' > ../gradlew && \
+        chmod +x ../gradlew && \
+        export ANDROID_NDK_ROOT=$ANDROID_NDK && \
+        export ANDROID_ABI="armeabi-v7a arm64-v8a x86" && \
+        cd ../../ && \
+        ./compile.sh release
+    ndk=r15c
 
-echo 'export PATH=$PATH:${ANDROID_HOME}/tools:${ANDROID_HOME}/platform-tools:/opt/gradle/bin' >> $bsenv
+Maintainer Notes:
+Ring has a lot of native dependencies, the source tarballs of these are all downloaded and build for all enabled architectures.
+We provide a fake gradlew because compile.sh calls this in the end.
+Build failed with swig 2.0.12 from jessie but works with 3.0.10 from jessie-backports.
+We don't build for x86_64 to reduce apk size a bit, x86 should work as well for those devices(?).
+We DO build separately for arm64 because this is a fairly common architecture and improves performance over using the armv7 binaries.
 .
 
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