docker: fix android build

Dockerfile.android

@@ -1,4 +1,4 @@
-FROM debian:buster
+FROM ubuntu:20.04
 
 ARG THREADS=1
 ARG ANDROID_NDK_REVISION=23c
@@ -20,6 +20,7 @@ ENV JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
 ENV PATH=${JAVA_HOME}/bin:${PATH}
 ENV PREFIX=${WORKDIR}/prefix
 ENV TOOLCHAIN_DIR=${ANDROID_NDK_ROOT}/toolchains/llvm/prebuilt/linux-x86_64
+ENV DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update \
     && apt-get install -y ant automake build-essential ca-certificates-java file gettext git libc6 libncurses5 \