Freshclam: Download whole CVD if failure applying CDIFF

In the event that there is an issue with the CDIFF process, freshclam is
treating it as thought no patch was downloaded.

If freshclam fails to apply the patch because of an issue with the
patch, or some bug in the CDIFF module, it should retry for the whole
CVD.

libfreshclam/libfreshclam_internal.c

@@ -2351,6 +2351,7 @@ fc_error_t updatedb(
 
         if (
             (FC_EEMPTYFILE == ret) ||                                 /* Request a new CVD if we got an empty CDIFF.      */
+            (FC_EFAILEDUPDATE == ret) ||                              /* Request a new CVD if we failed to apply a CDIFF. */
             (FC_SUCCESS != ret && (                                   /* Or if the incremental update failed:             */
                                    (0 == numPatchesReceived) &&       /* 1. Ask for the CVD if we didn't get any patches, */
                                    (localVersion < remoteVersion - 1) /* 2. AND if we're more than 1 version out of date. */