Unable to build BETA7 world. (unwind-pe.h: No such file or directory)

I upgraded from 5.2.1 to BETA6 earlier, and now i'm trying to upgrade to BETA7.
The problem is, i can't get the world built, it always brakes at this point:

===> gnu/lib/libreadline/readline/doc
===> gnu/lib/libstdc++
ln -sf /usr/src/gnu/lib/libstdc++/../../../contrib/libstdc++/config/cpu/i486/atomicity.h
atomicity.cc
rm -f .depend
....(lots of output here, no errors)....
/usr/src/gnu/lib/libstdc++/../../../contrib/libstdc++/libsupc++/vterminate.cc   
/usr/src/gnu/lib/libstdc++/../../../contrib/libstdc++/libsupc++/eh_personality.cc:38:23:
unwind-pe.h: No such file or directory
mkdep: compile failed
*** Error code 1

Stop in /usr/src/gnu/lib/libstdc++.
*** Error code 1

Stop in /usr/src/gnu/lib.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
koti# 

My make.conf has these:
CPUTYPE?=athlon-xp
CFLAGS=    -O -pipe -mmmx -msse
CXXFLAGS=  -O -pipe -mmmx -msse

I also tried with just "-O -pipe" and commented out the CPUTYPE, didn't.
Then i tried to build it with the gcc34 from ports, same error.
So i'd be glad if anyone could tell me how fix this.

Sorry if my reply-to isn't freebsd-current_at_freebsd.org, i cant change it :)