[CMake] Problem building libraries with no sources with Visual Studio 9 (2008)

[Pere Mato Vila]

> ADD_CUSTOM_COMMAND(
>    OUTPUT {library}.def
>    COMMAND <using ${library}-static>
>    COMMAND ${CMAKE_COMMAND} -E touch ${library}.cpp
>    DEPENDS ${library}-static
> )
> 
> This would invalidate ${library}.cpp each time ${library}.def is
> regenerated, so the dummy is recompiled and ${library} relinked.


 Many thanks for the hint.


Pere