Don't call utime() on the node.dab file for every read

... this was the cause of some observed unnecessarily high disk/file server
(Samba) utilization, as we call getnodedat() a lot. utime() opens and closes
the file, which was already open - and we're not modifying the file, so
updating the 'modification time' here is wrong anyway.

Disabling this 21-year old bit of logic resulted in a pretty dramatic
reduction in Samba (smbd) CPU utilization on Vertrauen.

If a BBS actually needes this hack (e.g. for NFS compatibility, as Deuce
eluded in the comment), they'd be better off just setting the "Keep Node File
Open" node setting (in SCFG->Nodes) to "No".

src/sbbs3/getnode.cpp

@@ -52,9 +52,10 @@ int sbbs_t::getnodedat(uint number, node_t *node, bool lockit)
 			return(errno); 
 		}
 	}
+#if 0 // This leads to high disk (or Samba/file server) utilization as we call getnodedat() a lot
 	else
 		utime(str,NULL);		/* NFS fix... utime() forces a cache refresh */
-
+#endif
 	number--;	/* make zero based */
 	for(count=0;count<LOOP_NODEDAB;count++) {
 		if(count)