Thank you Jules & Fabian for integrating my patch request, you can now declare library imports for Android projects directly in Introjucer.
You will need to define a seperate Android.mk file for your library (if it does not have one already), and store its location in the NDK_MODULE_PATH environment variable. It was done this way to keep things simple on the JUCE side.
I've put up a working example from my current project, using an Android build of the Aubio library: https://github.com/adamski/aubio-android