menuselect: Tweak check for recently run configure.

Recently menuselect has randomly produced an error stating that
configure was just run and make had to be restarted.  I believe this is
due to an incorrect menuselect/Makefile rule.  The original rule
produced an error if makeopts or autoconfig.h were older than
makeopts.in or autoconfig.h.in.  I believe this can create an issue if
makeopts is older than autoconfig.h.in or if autoconfig.h is older than
makeopts.in.  The new rules compare files independently.

Change-Id: Ibca155035fa1392c95e33cbf25f257902abba17b