Fix 30-year-old bug (obvious password patterns) in chkpass()

Off-by-one bug caused the comparison of only the first 3 chars of the proposed password against "QWE", "ASD", and "!@#" rather than the 4 character pattern match as intended.

These lines should be removed anyway since this can be easily achieved via password.can (as intended), but I couldn't help myself but to fix this ancient bug.

src/sbbs3/str.cpp

@@ -761,9 +761,9 @@ bool sbbs_t::chkpass(char *passwd, user_t* user, bool unique)
 			&& (strstr(pass,cfg.sys_id) || strstr(cfg.sys_id,pass)))
 		|| (cfg.node_phone[0] && strstr(pass,cfg.node_phone))
 		|| (user->phone[0] && strstr(user->phone,pass))
-		|| !strncmp(pass,"QWER",3)
-		|| !strncmp(pass,"ASDF",3)
-		|| !strncmp(pass,"!@#$",3)
+		|| !strncmp(pass,"QWER",4)
+		|| !strncmp(pass,"ASDF",4)
+		|| !strncmp(pass,"!@#$",4)
 		)
 		{
 		bputs(text[PasswordObvious]);