[CMake] Recursively add directories to INCLUDE_DIRECTORIES

[GOO Creations]

Hi all,

I want to recursively scan all sub-directories (and their 
sub-directories, etc ...) and determine if the directory contains a 
header (.h) file. I then want to add this directory to INCLUDE_DIRECTORIES.

The best thing (according to my CMake knowledge) is to write a macro for 
this and then use it as follows:

SCAN_DIRS(mylist)
INCLUDE_DIRECTORIES(${mylist})

Any suggestions on how to implement this "SCAN_DIRS" macro?

Christoph