Using SMB_DUPE_MSG macro for smb_addcrc return value test.

src/sbbs3/qwktomsg.cpp

@@ -351,7 +351,7 @@ bool sbbs_t::qwktomsg(FILE *qwk_fp, char *hdrblk, char fromhub, uint subnum
 
 		j=smb_addcrc(&smb,crc);
 		if(j) {
-			if(j==1) {
+			if(j==SMB_DUPE_MSG) {
 				bprintf("\r\nDuplicate message\r\n");
 				if(!fromhub) {
 					if(subnum==INVALID_SUB) {

src/sbbs3/sbbsecho.c

@@ -2600,7 +2600,7 @@ int fmsgtosmsg(uchar HUGE16 *fbuf, fmsghdr_t fmsghdr, uint user, uint subnum)
 		crc=~crc;
 		i=smb_addcrc(&smb[cur_smb],crc);
 		if(i) {
-			if(i==1)
+			if(i==SMB_DUPE_MSG)
 				printf("Duplicate ");
 			else
 				printf("smb_addcrc returned %d ",i);