(ITS#6391) missing check for broken filters

[h.b.furuseth@usit.uio.no]

Full_Name: Hallvard B Furuseth
Version: HEAD
OS: 
URL: 
Submission from: (NULL) (129.240.6.233)
Submitted by: hallvard


syncrepl.c and overlays/pcache.c call str2filter() and str2filter_x()
without checking for success.

(so does retcode, but that overlay is only for testing anyway.)