bus-unit-util: fix bus_wait_for_jobs() debug output (#8760)

We shouldn't print 'errno' if its not initialized properly.

src/shared/bus-unit-util.c

@@ -1971,6 +1971,8 @@ int bus_wait_for_jobs(BusWaitForJobs *d, bool quiet, const char* const* extra_ar
                         if (q < 0 && r == 0)
                                 r = q;
 
+                        errno = 0; /* Reset errno explicitly, so that log_debug_errno() will properly print 'Success'
+                                    * for q == 0, instead of whatever is set in errno */
                         log_debug_errno(q, "Got result %s/%m for job %s", strna(d->result), strna(d->name));
                 }