+/// Returns a directory containing system-wide architecture-specific files.
+Path get_sys_lib_dir();
+
+/** Looks for a file in a list of paths. Returns the absolute path to the
+first existing location, or an empty Path if the file is not found at all. */
+Path path_lookup(const std::string &, const std::list<Path> &);
+
+/** Looks for a file using the PATH environment variable. */
+Path path_lookup(const std::string &);