[CMake] autoheader

[Bill Hoffman]

Marcel Loose wrote:
> Hi Bill,
> 
> Wouldn't it be better if CMake kept track of these variables internally.
> I mean, usually the HAS_X variables are the result of calls to
> check_include_file() and check_function_exists(). The Autotools handle
> this under the hood.
> CMake might keep a list of these variables, possibly one per check_*()
> function. Or is there a reason to let the user handle this explicitly by
> specifying the list of HAS_X variables in the call to
> cmake_autoheader()?
> 

check_include_file does not even have to be used, there are lots of ways 
to come up with variables that might be useful in a configured header 
file. I don't really like magic behind the scene lists getting created. 
Someone could just use a macro for check_include_file that appends to a 
list if they wanted.

-Bill