sysupdate: print assumed value

The MatchPattern= in Target specification is documented as mandatory,
but if not defined sysupdate will assume the same value as definied
in Source specification and continue execution. Print this
assumptions to the user

src/sysupdate/sysupdate-transfer.c

@@ -532,6 +532,7 @@ int transfer_read_definition(Transfer *t, const char *path) {
                                   "Target path is not a normalized, absolute path: %s", t->target.path);
 
         if (strv_isempty(t->target.patterns)) {
+                log_info("Target specifications lacks MatchPattern=. Assuming same value as in Source specification");
                 strv_free(t->target.patterns);
                 t->target.patterns = strv_copy(t->source.patterns);
                 if (!t->target.patterns)