Folder History is not working anymore.

BUG: 379177

Commit 840d1c40bc906b0961418c8b738aef3971e7dce2 broke it.

QStandardPaths::locate(QStandardPaths::AppLocalDataLocation, "recentfolders/")

always returns an empty string "" when either the recentfolders folder or the ~/.local/share/gwenview folder don't exist.
See: http://doc.qt.io/qt-5/qstandardpaths.html#locate

If no such file or directory can be found, an empty string is returned

KStandardDirs::locateLocal behaves differently (from the api doc)

No check is made if the specified filename actually exists. Missing directories are created.

As we don't want to switch back to KStandardDirs I came up with a working patch using QStandardPaths::writableLocation (see attachment) as

Note: The storage location returned can be a directory that does not exist; i.e., it may need to be created by the system or the user.

(from : http://doc.qt.io/qt-5/qstandardpaths.html#writableLocation )