docs: update readme for ndk (#639)

* doc: update readme for ndk

* rephrase

* update docs

* update doc

README.md

@@ -25,6 +25,9 @@ Any data transfer from or to the app happens using QR code. By doing so, the mos
 - [Troubleshooting](https://github.com/paritytech/parity-signer/wiki/Troubleshooting)
 - [Publishing](https://github.com/paritytech/parity-signer/wiki/Publishing)
 
+## Changes from 4.3.1
+From [4.3.1](https://github.com/paritytech/parity-signer/commit/ea5786c85661d9b176795b9386af640b3e73aff3) we use the latest prebuild NDK (r21) toolchains for building rust libraries for android, so that we do not need to build the standalone NDK toolchains manually. If you have built or develop Parity Signer before 4.3.1, please download the NDK r19 or newer[here](https://developer.android.com/ndk/downloads) and point the `NKD_HOME` environment variable to it with e.g. `export NDK_HOME=/path/to/latest/ndk`
+
 ## License
 
 Parity-Signer is [GPL 3.0 licensed](LICENSE).

scripts/build.sh

-#!/bin/bash
-
-source ./scripts/variables.sh
-
-# Build iOS
-cd ./rust/signer
-
-cargo lipo --release
-
-cp "./target/universal/release/lib${LIB_NAME}.a" "../../ios/lib${LIB_NAME}.a"
-
-# Build android
-
-if [ -z ${NDK_HOME+x} ];
-  then
-    printf 'Please install android-ndk\n\n'
-    printf 'from https://developer.android.com/ndk/downloads or with sdkmanager'
-    exit 1
-  else
-    printf "Building Andriod targets...";
-fi
-
-CC_aarch64_linux_android="${ANDROID_PREBUILD_BIN}/aarch64-linux-android${API_LEVEL}-clang" \
-CARGO_TARGET_AARCH64_LINUX_ANDROID_LINKER="${ANDROID_PREBUILD_BIN}/aarch64-linux-android${API_LEVEL}-clang" \
-  cargo build --target aarch64-linux-android --release
-
-CC_armv7_linux_androideabi="${ANDROID_PREBUILD_BIN}/armv7a-linux-androideabi${API_LEVEL}-clang" \
-CARGO_TARGET_ARMV7_LINUX_ANDROIDEABI_LINKER="${ANDROID_PREBUILD_BIN}/armv7a-linux-androideabi${API_LEVEL}-clang" \
-  cargo build --target armv7-linux-androideabi --release
-
-CC_i686_linux_android="${ANDROID_PREBUILD_BIN}/i686-linux-android${API_LEVEL}-clang" \
-CARGO_TARGET_I686_LINUX_ANDROID_LINKER="${ANDROID_PREBUILD_BIN}/i686-linux-android${API_LEVEL}-clang" \
-  cargo  build --target i686-linux-android --release
-
-CC_x86_64_linux_android="${ANDROID_PREBUILD_BIN}/x86_64-linux-android${API_LEVEL}-clang" \
-  CARGO_TARGET_X86_64_LINUX_ANDROID_LINKER="${ANDROID_PREBUILD_BIN}/x86_64-linux-android${API_LEVEL}-clang" \
-      cargo  build --target x86_64-linux-android --release
-
-for i in "${!ANDROID_ARCHS[@]}";
-  do
-    mkdir -p "../android/src/main/${ANDROID_FOLDER[$i]}"
-    cp "./target/${ANDROID_ARCHS[$i]}/release/lib${LIB_NAME}.so" "../android/src/main/jniLibs/${ANDROID_FOLDER[$i]}/lib${LIB_NAME}.so"
-done