libstdc++-v3/std_cstddef.h's #include_next x libg++

[Benjamin Kosnik]

> > Shouldn't you be using INCLUDES from libstdc++-v3/src/Makefile.am:
> 
> Great!  That's the clue I was missing.  Ok to install?

Please do..........

(FYI at some point, I'd like to make things like INCLUDES go into the 
top-level Makefile.am, instead of being duplicated in the src/Makefile.am 
and libio/Makefile.am. I think I tried to do this once but it wasn't 
working and I gave up quickly (should this be possible?) . When/if I do 
this, will this bit need to be changed? )

thanks, benjamin