Map tile cache location doesn't work under AppArmor confinement use case

The QtLocation library itself defaults to caching map tiles in

QStandardPaths::writableLocation(QStandardPaths::GenericCacheLocation) + QLatin1String("/QtLocation")

typically on Unix this will be

~/.cache/QtLocation

There's no way to override this without changing the code as far as I've seen.

Now my use case is a very strict AppArmor environment where applications cannot share most files with other applications to prevent privacy leaks. The ability to see which maps were being browsed by inspecting the tile cache is not acceptable here.

Simple solution:

QStandardPaths::writableLocation(QStandardPaths::CacheLocation)

which will end up storing tiles in

~/.cache/myAppName

I understand this may not be desirable for everyone so this probably isn't a sufficient solution. Though if it is, I've got a patch for that.

Another option might be a build flag.

A third option I brainstormed with a few people is API that is aware of confinement such that it's aware if the underlying platform plugin is "confined". Though this isn't so obvious as there's no other code doing this so far (that I'm aware of).