Android: provide Dockerfile and use it for GitalbCI

Add support for installing Android SDK NDK directly into
  prepare-toolchain-clang.sh
Modernize prepare-toolchain-clang.sh
Add support to install Qt based on installer 4.X to prepare-toolchain-clang.sh
Setub GtlabCI to build android APK based on the produced Docker image

build_scripts/Android/Dockerfile

@@ -0,0 +1,118 @@
+## To prepare an image suitable as base for Gitlab CI use
+## image name must match gitlab repository name, you can play just with the tag
+## the part after :
+# export CI_IMAGE_NAME="registry.gitlab.com/retroshare/retroshare:android_arm_base"
+# docker build --squash -t "${CI_REGISTRY_IMAGE}" \
+# --build-arg QT_INSTALLER_JWT_TOKEN="your qt JWT token goes here"  .
+#
+# To build Android ARMv8 (64 bit) package pass also
+# export CI_IMAGE_NAME="registry.gitlab.com/retroshare/retroshare:android_arm64_base"
+# --build-arg ANDROID_NDK_ARCH=arm64 --build-arg ANDROID_PLATFORM_VER=21
+
+## --squash is very important in case of GitlabCI shared runners as they are
+## limited to 25GB disk size
+
+## To push it to gitlab CI registry you need first to login and the to push
+# docker login registry.gitlab.com
+# docker push ${CI_IMAGE_NAME}
+
+
+FROM ubuntu:20.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get clean
+RUN apt-get install -y -qq \
+	bash build-essential bzip2 cmake curl chrpath doxygen \
+	git p7zip python qt5-default qttools5-dev tclsh unzip wget zip
+
+# Dependencies to create Android pkg
+RUN apt-get install -y -qq \
+	openjdk-8-jre openjdk-8-jdk openjdk-8-jdk-headless gradle
+
+ARG FRESHCLONE=0
+ARG REPO_URL=https://gitlab.com/RetroShare/RetroShare.git
+ARG REPO_BRANCH=master
+ARG REPO_DEPTH="--depth 2000"
+
+RUN git clone $REPO_DEPTH $REPO_URL -b $REPO_BRANCH && cd RetroShare && \
+	git fetch --tags
+
+ENV PREPARE_TOOLCHAIN="/RetroShare/build_scripts/Android/prepare-toolchain-clang.sh"
+ENV NATIVE_LIBS_TOOLCHAIN_PATH="/android-toolchain/"
+
+ARG ANDROID_PLATFORM_VER=16
+ARG ANDROID_NDK_ARCH=arm
+
+ENV ANDROID_SDK_PATH="/opt/android-sdk"
+ENV ANDROID_HOME="$ANDROID_SDK_PATH"
+ENV ANDROID_SDK_ROOT="$ANDROID_SDK_PATH"
+
+ENV ANDROID_NDK_PATH="/opt/android-ndk"
+ENV ANDROID_NDK_ROOT="$ANDROID_NDK_PATH"
+
+ENV PATH="$PATH:$ANDROID_HOME/tools"
+ENV PATH="$PATH:$ANDROID_HOME/platform-tools"
+ENV JAVA_HOME="/usr/lib/jvm/java-8-openjdk-amd64/"
+
+RUN mkdir /bCache
+WORKDIR /bCache
+
+## Quick HACK to ease development
+#COPY prepare-toolchain-clang.sh $PREPARE_TOOLCHAIN
+
+RUN $PREPARE_TOOLCHAIN install_android_sdk
+RUN $PREPARE_TOOLCHAIN install_android_ndk
+RUN $PREPARE_TOOLCHAIN bootstrap_toolchain
+RUN $PREPARE_TOOLCHAIN build_bzlib
+RUN $PREPARE_TOOLCHAIN build_openssl
+RUN $PREPARE_TOOLCHAIN build_sqlite
+RUN $PREPARE_TOOLCHAIN build_sqlcipher
+RUN $PREPARE_TOOLCHAIN build_rapidjson
+RUN $PREPARE_TOOLCHAIN build_restbed
+RUN $PREPARE_TOOLCHAIN build_udp-discovery-cpp
+RUN $PREPARE_TOOLCHAIN build_xapian
+RUN $PREPARE_TOOLCHAIN build_miniupnpc
+RUN $PREPARE_TOOLCHAIN deduplicate_includes
+
+ARG QT_INSTALLER_JWT_TOKEN
+RUN $PREPARE_TOOLCHAIN install_qt_android
+# Avoid Qt account details leak into the image
+RUN rm -f /root/.local/share/Qt/qtaccount.ini
+# Shrink image by removing unneded Qt components
+RUN rm -r \
+	$NATIVE_LIBS_TOOLCHAIN_PATH/Qt/Docs/ \
+	$NATIVE_LIBS_TOOLCHAIN_PATH/Qt/Examples/ \
+	$NATIVE_LIBS_TOOLCHAIN_PATH/Qt/Tools/ 
+
+RUN mkdir /jsonapi-generator-build
+WORKDIR /jsonapi-generator-build/
+RUN qmake ../RetroShare/jsonapi-generator/src/ \
+		CONFIG+=no_retroshare_plugins \
+		CONFIG+=no_retroshare_service CONFIG+=no_retroshare_gui \
+		CONFIG+=rs_jsonapi && \
+	make -j$(nproc)
+
+#CONFIG+=no_keywords
+RUN mkdir /retroshare-service-android-build
+WORKDIR /retroshare-service-android-build
+RUN $($PREPARE_TOOLCHAIN get_qt_dir | head -n 1)/bin/qmake ../RetroShare \
+	-spec android-clang \
+	CONFIG+=retroshare_service CONFIG+=rs_jsonapi \
+	RS_UPNP_LIB=miniupnpc \
+	JSONAPI_GENERATOR_EXE=/jsonapi-generator-build/jsonapi-generator \
+	NATIVE_LIBS_TOOLCHAIN_PATH=$NATIVE_LIBS_TOOLCHAIN_PATH \
+	CONFIG+=no_retroshare_gui CONFIG+=no_rs_service_webui_terminal_password \
+	CONFIG+=no_rs_service_terminal_login
+RUN	make -j$(nproc)
+RUN make install INSTALL_ROOT=/retroshare-service-android-build/android-build/
+RUN $($PREPARE_TOOLCHAIN get_qt_dir | head -n 1)/bin/androiddeployqt \
+	--input retroshare-service/src/android-libretroshare-service.so-deployment-settings.json \
+	--output android-build --android-platform android-$ANDROID_PLATFORM_VER \
+	--jdk $JAVA_HOME --gradle
+
+
+RUN rm -rf /bCache
+
+# Clean apt cache
+RUN apt-get clean && rm -rf /var/lib/apt/lists/*