Update qbs submodule to HEAD of master branch.

Includes some necessary adaptations to the QbsProjectManager plugin,
namely:
    - Use the new library for setting up Qt profiles.
    - Use per-profile preferences.

Change-Id: I0a639bd291d790c6da9cb4ade53841314310d5ef
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>