Use new NDK in x86-64 Android Dockerfile

Author: workingjubilee

ci/docker/x86_64-linux-android/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:16.04
+FROM ubuntu:20.04
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
@@ -14,16 +14,16 @@ RUN apt-get update && \
 WORKDIR /android/
 ENV ANDROID_ARCH=x86_64
 COPY android-install-ndk.sh /android/
-RUN sh /android/android-install-ndk.sh $ANDROID_ARCH
+RUN sh /android/android-install-ndk.sh
 
 # We do not run x86_64-linux-android tests on an android emulator.
 # See ci/android-sysimage.sh for informations about how tests are run.
 COPY android-sysimage.sh /android/
 RUN bash /android/android-sysimage.sh x86_64 x86_64-24_r07.zip
 
-ENV PATH=$PATH:/rust/bin:/android/ndk-$ANDROID_ARCH/bin \
-    CARGO_TARGET_X86_64_LINUX_ANDROID_LINKER=x86_64-linux-android-gcc \
-    CC_x86_64_linux_android=x86_64-linux-android-gcc \
-    CXX_x86_64_linux_android=x86_64-linux-android-g++ \
-    OBJDUMP=x86_64-linux-android-objdump \
+ENV PATH=$PATH:/rust/bin:/android/ndk/toolchains/llvm/prebuilt/linux-x86_64/bin \
+    CARGO_TARGET_X86_64_LINUX_ANDROID_LINKER=x86_64-linux-android21-clang \
+    CC_x86_64_linux_android=x86_64-linux-android21-clang \
+    CXX_x86_64_linux_android=x86_64-linux-android21-clang++ \
+    OBJDUMP=llvm-objdump \
     HOME=/tmp