Really fix the relative timestamp bug. It was only incorrect for the ALQ

case.  It seems entries are in reverse order when read from the kernel
memory but in the right order when read from a file (i.e. ALQ).  Handle
both cases.

MFC after:	1 day

usr.bin/ktrdump/ktrdump.c

@@ -253,7 +253,8 @@ main(int ac, char **av)
 			if (rflag) {
 				if (tlast == -1)
 					tlast = tnow;
-				fprintf(out, "%16ju ", tnow - tlast);
+				fprintf(out, "%16ju ", !iflag ? tlast - tnow :
+				    tnow - tlast);
 				tlast = tnow;
 			} else
 				fprintf(out, "%16ju ", tnow);