[build2] Trigger compile of sources when their header dependencies change

[Boris Kolpackov]

Hi Max,

Moldmann Max (DC-MA/ENG52-NA) <Max.Moldmann at boschrexroth-us.com> writes:

> I noticed that build2 doesn't compile file-a.c when an included header
> file i.e. file-a.h is changed.

That's strange, this feature has been implemented and working for us
for a long time now. You can check for this header in the "aux 
dependency database" file (file-a.o.d).

If this indeed does not work, I will need a simple project that
reproduces this problem as well as the description of the environment
(if this is Windows, perhaps it has something to do with timestamp
resolution...).

Boris