Don't hash messages with invalid message numbers

It's better to have deleted messages without a hash than to hash invalid
message numbers.

This can be used to address a (renumbered?) message base that Kirkman
shared with me with "Invalid Message number" chksmb warnings from hash
entries with message numbers > than the base's last_msg.

src/sbbs3/fixsmb.c

@@ -243,6 +243,10 @@ int fixsmb(char* sub)
 		else if(smb_undelete)
 			msg.hdr.attr&=~MSG_DELETE;
 
+		if(renumber)
+			msg.hdr.number=n+1;
+
+		if(renumber || msg.hdr.number <= last_msg) {
 			/* Create hash record */
 			if(msg.hdr.attr&MSG_DELETE)
 				text=NULL;
@@ -253,6 +257,7 @@ int fixsmb(char* sub)
 				printf("!ERROR %d hashing message\n", i);
 			if(text!=NULL)
 				free(text);
+		}
 
 		/* Index the header */
 		if(dupe_msgnum)
@@ -263,8 +268,6 @@ int fixsmb(char* sub)
 			printf("Not indexing invalid message number (0)!\n");
 		else {
 			msg.idx_offset=n;
-			if(renumber)
-				msg.hdr.number=n+1;
 			if(msg.hdr.number > highest)
 				highest = msg.hdr.number;
 			if(msg.hdr.netattr&MSG_INTRANSIT) {