Well, I think I've figured it out.  I went through ExtUtils::MM_Unix
and tore out all the seemingly unnecessary -I$(PERL_LIB)
-I$(PERL_ARCH) and tried to build the core.  Dynaloader exploded.

What it appears they're for is building core extensions.  Since perl
isn't installed yet, its @INC is all wrong.  -I$(PERL_LIB) adds in
things like ../../lib so it can see its own libraries before
installation when building things like ext/Dynaloader/.

This really shouldn't be leaking out of the core.  I'm trying to
rewire it so MakeMaker only adds the extra -I's when building the core
and leaves them out otherwise.  Anyone think of a good way to detect
when we're building a core module?  Would it be too much to require an
IS_CORE flag in the Makefile.PL's?


-- 
Michael G Schwern   <schwern@[...].com>    http://www.pobox.com/~schwern/
Perl6 Quality Assurance     <perl-qa@[...].org>        Kwalitee Is Job One