[CMake] --enable-* with cmake

[Bill Hoffman]

Brandon Van Every wrote:
>
>
> It might be reasonable, however, to show OPTIONS resolved at the
> current scope.  And to note whether conditional options exist, i.e.
> "Warning: conditional options detected.  You are advised to run
> (CMakeSetup|CCMake) and resolve them iteravely."  Or the opposite:
> "All options have been resolved."
>   
There is no way to do this, because the code inside an if(FALSE) is 
never run, so there
would be no way to know if an option command was being skipped.  
> Is it possible to resolve them iteravely from the command line?  I've
> had no reason to try that, but in principle, could you hammer the
> cache over and over again until it worked?  You'd need feedback to
> know what the conditional options are.  Is there any mechanism to do
> that at present, or do we need the OPTIONS readout as suggested above?
>   
cmake -i will do that.

-Bill