kconfiglib/menuconfig: Various improvements

Update Kconfiglib and menuconfig to upstream revision e47d7eff1012e, to
add some small fixes/improvements/changes:

 - Raise errors for extra trailing tokens anywhere. They were silently
   ignored in some places:

     * end{if,menu,choice} <extra tokens>

     * {default,select,...} FOO <extra tokens>  (though e.g.
       'default FOO if' raised an error)

 - Rephrase the warning when selecting a choice symbol to make it
   clearer that select never has any effect on choice symbols.

 - Display empty menus with '----' instead of '---> (empty)'. This
   matches the C tools. It might be less confusing for symbols defined
   with 'menuconfig', which is where you most often get empty menus
   (when the symbol is n).

 - Speed up parsing performance

Signed-off-by: Ulf Magnusson <[email protected]>

Author: ulfalizer