cvmfs_search cache can grow without bound

[DrDaveD]

I don't see anything in cvmfs_search that cleans up old cache items. I think the cached files should go somewhere that gets automatically cleaned up, $TMPDIR or /tmp if $TMPDIR is not set. That's what the other utlls do.

@Vbitz what do you think?

[DrDaveD]

In order to be reusable it will need a directory name associated with the user of course, maybe ${TMPDIR:-/tmp}/cvmfs_search_$(id -u)/ in bash terms.

[Vbitz]

That sounds reasonable.

The index can take some time to populate for large CVMFS repositories and it may be worth looking at future optimisations in the library itself.