feat(docker): Set the ANDROID_SDK_ROOT environment variable

The variable is required by old Android projects which use a version of
the Gradle Android plugin that does not yet support `ANDROID_HOME`. Also
see [1].

[1]: https://developer.android.com/tools/variables#envar

Signed-off-by: Martin Nonnenmacher <[email protected]>

Author: mnonnenmacher

Dockerfile

@@ -526,6 +526,7 @@ ARG PHP_VERSION
 
 # Repo and Android
 ENV ANDROID_HOME=/opt/android-sdk
+ENV ANDROID_SDK_ROOT=$ANDROID_HOME
 ENV ANDROID_USER_HOME=$HOME/.android
 ENV PATH=$PATH:$ANDROID_HOME/cmdline-tools/latest/bin:$ANDROID_HOME/cmdline-tools/bin
 ENV PATH=$PATH:$ANDROID_HOME/platform-tools