This is a simple patch implementing a dedicated KDevelop temporary directory (on Unix). With this, every session has its own directory for temporary files under the default QSP::TempLocation directory, set via the TMPDIR env. variable. The clang parser's preamble* files go here, for instance, but also any files the session creates under QSP::TempLocation itself.
The entire directory is removed during a clean exit, and also at startup. This takes care of preventing the accumulation of (large) old temporary files I tend to get on Mac.