Provide androiddeployqt with all prefix paths

Summary:
This is needed for a new feature in Qt 5.12, making androiddepolyqt's
recursive dependency resolution avaiable for components installed in
different prefixes too.

This will allow us to drop our own partial ELF dependency parsing code
eventually, as well as avoid having to do workarounds like linking against
all indirect dependencies.

Reviewers: Build System, apol

Reviewed By: apol

Subscribers: Frameworks

Tags: Frameworks, Build System

Differential Revision: https://phabricator.kde.org/D11388