[Development] Modify QLibraryInfo to support any default location of qt.conf

[Welbourne Edward]

Maximilian Hrabowski (28 January 2016 10:47):
> What we need is a way to look up the qt.conf at another location as well.
[...]
> I thought about the following ways (order gives my personal opinion’s priority):
>
> 1. Add a new public API: static void QLibraryInfo::setQtConfFilePath(
> const QString& filePath) which defaults to ":/qt/etc/qt.conf“ and is
> used in QSettings *QLibraryInfoPrivate::findConfiguration() instead of
> the hard-coded path.

How does this help in your scenario ?
How would your launcher get to know what path to use ?

> 2. Also lookup qt.conf in all of QLibraryInfo::libraryPaths() (this is
> how we got the plugins found)

Potentially problematic if plugins might install a qt.conf that isn't
what your application needs.

> 3. introduce an environment variable that points to the qt.conf
> similar to the one of QWebEngineProcess.exe

Why isn't this first ?
I would generally expect an environment variable to take precedence over
all other configuration options except command-line options.

	Eddy.