[CMake] file not generated with ADD_CUSTOM_COMMAND

[Brad King]

Alexander Neundorf wrote:
>>Double-quote includes look for the source files in the directory  
>>containing the source, not in the current working directory of the  
>>compiler.  For an out-of-source build the directory in which the header  
>>is generated is not the one containing the source file.   
>  
> Yes, but I didn't build out-of-source, so the generated file was in the 
> same directory as the source file. 

This is a bug in the dependency scanning not in custom commands.  I 
suspect this will be resolved in our other thread on dependencies.

-Brad