Better support for custom commands that generate multiple files needed.

[Brad King]

Joseph Wenninger wrote:
> I haven't looked that deep into cmake yet, but is there a reason, why it 
> doesn't it just allow multiple OUTPUT parameters ? (OUTPUT xyz OUTPUT 
> asdf  ....) ?
> 
> I don't know how portable it is and what happens with parallel builds, but at 
> least in gnu make you can write eg
> 
> y.tab.c y.tab.h: myfile.y
> 	yacc -d myfile.y
> 
> And the it usually works for me if a helper command generates more than one 
> output file

There is no reason except that it hasn't been implemented in CMake.  I'm 
working on it now.  AFAIK this multiple-output syntax works in all makes 
supported by CMake.  There is also similar support in Visual Studio 
project files.

-Brad