Fix #CR-633 in oxcfxics on folder change

Set retval while getting specific props from a openchange db table row.

The problem comes from the `retvals[i]` is overwritten in L1789 so we
have to store the retval in the local variable likewise other switch
functions does.
Merge pull request #132 from sixstone-qq/ejhernandez/fix-crash-folder-change-oc-db-folder

Fix #CR-633 in oxcfxics on folder change