[Vala] Debugging the compiler command generated by valac

[Joe Sapp <nixphoeni gmail com>]

I'm having an issue with the C compiler command generated by valac.
Specifically, an include directory is being included unexpectedly (see
[1]).  Is there any way to figure out what causes this to happen, or
which package or file is at fault?  I can't seem to find any way to
get intermediate information between the `valac` call and the `cc`
call.

-- 
Thanks,
Joe Sapp

[1] https://bugs.gentoo.org/show_bug.cgi?id=492480#c5