Revert part of the previous revision. Changing exit() to return() in main()

is wrong, even though our C compiler doesn't understand that exit() eats
control of the program, and as such can sometimes complain that main() reaches
the bottom of its body without an explicit return().

Aside from that, the functional usefulness of changing it is effectively nil,
so back it out.

Submitted by:	mike

usr.bin/tee/tee.c

@@ -121,7 +121,7 @@ main(argc, argv)
 		}
 	if (rval < 0)
 		err(1, "read");
-	return (exitval);
+	exit(exitval);
 }
 
 static void