Fix issue #536 -- If a prefix to the named cache directory is absent, create is when the cache directory is created.
Fix issue #536 -- If a prefix to the named cache directory is absent, create is when the cache directory
is created.

HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit