NDK fixes.

Author: Alexhuszagh

docker/android-ndk.sh

@@ -21,7 +21,7 @@ NDK_URL="https://dl.google.com/android/repository/${NDK_FILENAME}"
 main() {
     local arch="${1}"
 
-    install_packages curl unzip
+    install_packages curl unzip python
 
     local td
     td="$(mktemp -d)"
@@ -31,7 +31,10 @@ main() {
     unzip -q "${NDK_FILENAME}"
     rm "${NDK_FILENAME}"
     pushd "android-ndk-${ANDROID_NDK}"
-    mv "toolchains/llvm/prebuilt/${NDK_PLATFORM}" /android-ndk
+    ./build/tools/make_standalone_toolchain.py \
+        --install-dir /android-ndk \
+        --arch "${arch}" \
+        --api "${ANDROID_SDK}"
 
     # clean up unused toolchains to reduce image size
     local triple