Fix coverity issues

:Release Notes:
Fixed uninitialized CFileCacheSet field
Fixed exception handling during directory cleanup

:Detailed Notes:

:Testing Performed:
Unit-tests.

:QA Notes:

:Issues Addressed:
[GF-53048] Filecache: fix coverity issues

Open-webOS-DCO-1.0-Signed-off-by: Alexandr Smoktal <alexandr.smoktal@lge.com>

Change-Id: I6e11a4a02baf588fbe5b85c45de049e48c483700
Reviewed-on: https://g2g.palm.com/4054
Reviewed-by: DCO Verification
Reviewed-by: Alexandr Smoktal <alexandr.smoktal@lge.com>
Tested-by: Alexandr Smoktal <alexandr.smoktal@lge.com>
Reviewed-by: Alekseyev Oleksandr <alekseyev.oleksandr@lge.com>