include legacy pre-multiarch plugin paths

include legacy pre-multiarch plugin paths

Last-Update: 2012-04-25

A full multiarch system requires an architecture-qualified plugin path for
Qt, but installed systems may still have plugins (e.g., from other
distribution packages) in another pre-multiarch directory.  When constructing
the plugin path, include both the configured plugin path and a plugin path
with the architecture triplet stripped out.

This applies to the general plugin loading system, and to the QML one.

Gbp-Pq: Name qt-multiarch-plugin-path-compat.diff