Delete the ndk directory in Dockerfile.

Dockerfile.android

@@ -5,10 +5,8 @@ ARG UBUNTU_MIRROR
 RUN /bin/bash -c 'if [[ -n ${UBUNTU_MIRROR} ]]; then sed -i 's#http://archive.ubuntu.com/ubuntu#${UBUNTU_MIRROR}#g' /etc/apt/sources.list; fi'
 
 ENV HOME=/root \
-    ANDROID_HOME=/opt/android-sdk-linux \
     ANDROID_NDK_HOME=/opt/android-ndk-linux \
-    ANDROID_STANDALONE_TOOLCHAIN=/opt/android-toolchain-gcc \
-    PATH=${PATH}:${ANDROID_HOME}:${ANDROID_NDK_HOME}
+    ANDROID_STANDALONE_TOOLCHAIN=/opt/android-toolchain-gcc
 
 RUN apt-get update && \
     apt-get install -y git python-dev python-pip python-numpy && \
@@ -38,6 +36,7 @@ RUN mkdir /opt/android-ndk-tmp && \
     unzip -q android-ndk-r14b-linux-x86_64.zip && \
     mv android-ndk-r14b ${ANDROID_NDK_HOME} && \
     ${ANDROID_NDK_HOME}/build/tools/make-standalone-toolchain.sh --arch=arm --platform=android-21 --install-dir=${ANDROID_STANDALONE_TOOLCHAIN} && \
-    rm -rf /opt/android-ndk-tmp
+    rm -rf /opt/android-ndk-tmp && \
+    rm -rf ${ANDROID_NDK_HOME}
 
 CMD ["bash", "/paddle/paddle/scripts/docker/build_android.sh"]

paddle/scripts/docker/build_android.sh

@@ -4,6 +4,7 @@ set -xe
 
 mkdir -p /paddle/build
 cd /paddle/build
+rm -f /paddle/install 2>/dev/null || true
 cmake -DCMAKE_SYSTEM_NAME=Android \
       -DANDROID_STANDALONE_TOOLCHAIN=$ANDROID_STANDALONE_TOOLCHAIN \
       -DANDROID_ABI=armeabi-v7a \