[CMake] Following dependencies through generated header file

[Óscar Fuentes]

A file `foo.cpp' has this:

#include "bar.inc"

`bar.inc' is a generated file, and is marked as such. It is generated
processing a file `zoo.cpp' with an utility executed through a custom
command.

It would be very convenient to inspect the header files referenced from
`zoo.cpp' and associate them with `bar.inc', so when some of those
header files are touched `bar.inc' (and hence `foo.cpp') is
automatically re-built.

Is this possible?