Keith Packard authored Oct 17, 2018 and Akira TAGOH committed Oct 25, 2018

Because FcDirCacheDeleteUUID does not reset the modification time on
the directory, and because FcDirCacheRead unconditionally creates the
UUID file each time it is run, any empty directory in the cache will
get its timestamp changed each time the cache for that directory is
read.

Instead, just leave the UUID file around as it is harmless.

The alternative would be to only create the UUID file after the cache
has been created and the directory has been discovered to be
non-empty, but that would delay the creation of the UUID file.

Signed-off-by: Keith Packard <keithp@keithp.com>