Revert "remove ANDROID_SDK_HOME, ANDROID_NDK_HOME env vars" (#102)

This reverts commit 1b7e96b.

Author: gengjiawen

Dockerfile

@@ -16,7 +16,9 @@ ARG WATCHMAN_VERSION=4.9.0
 # set default environment variables
 ENV ADB_INSTALL_TIMEOUT=10
 ENV ANDROID_HOME=/opt/android
+ENV ANDROID_SDK_HOME=${ANDROID_HOME}
 ENV ANDROID_NDK=${ANDROID_HOME}/ndk/$NDK_VERSION
+ENV ANDROID_NDK_HOME=${ANDROID_HOME}/ndk/$NDK_VERSION
 ENV JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
 
 ENV PATH=${ANDROID_NDK}:${ANDROID_HOME}/cmdline-tools/tools/bin:${ANDROID_HOME}/emulator:${ANDROID_HOME}/platform-tools:${ANDROID_HOME}/tools:${ANDROID_HOME}/tools/bin:/opt/buck/bin/:${PATH}