>> I'm going to be playing with it some more, trying to see if I can do
   >> an UNPRIVED build (which _can't_ overwrite /usr/include)
   > use DESTDIR; don't build to /.
   
   I've tried that.  Didn't work that way either.  Fell over because it
   tried to do a c++ compile depending on a bunch of files in
   $DESTDIR/usr/include/g++ before it installed them.  First
   <std/std_valarray.h>, then when I copied that one in by hand, it
   depended on half a dozen others.  I'm now trying to get
   $DESTDIR/usr/include/g++ built by hand enough for the build to work.


there is something very wrong with your setup.  i've done this multiple
times in the past few weeks, natively & cross, and it never has failed
for any reason that wasn't my own fault :-)


unfortunately, i don't know what the hell it is.  what, exactly, did it
try to do when it failed to c++ compile stuff?  i have this very vague
memory of builds failing like this once, and it had to do with .depend
files in the source tree that shouldn't have been there - are you 100%
sure your source tree is clean before the build starts?

note that with the presence of objdirs, etc, "make cleandir" is not
guarenteed to work 100% of the time :-(