> unfortunately, just because one of those headers _exists_ doesn't mean
> that the build will work sanely, or that the resulting binary will
> function properly when installed, especially on systems with shared
> libraries.
> 
> This becomes a serious problem when building distributions, etc.
> (for instance, on the machine that i built i386 snapshots on, the X11
> install was (is!) ancient.)

Sigh.  I tried to think of all the good reasons for not doing this before
submitting a pr, but I didn't think of building distributions.  Certainly
this would work for building on your own machine.  I'll think harder next
time.  ;-)

Dave