make buildworld error with current

Hi,

when trying to make a buildworld with the current cvs snapshot I get an 
error in /usr/src/lib/libc (regardless of multi-user / single-user). 
What I've tried so far is:

-) CPUTYPE?=athlon in make.conf
-) provide a TARGET_ARCH=i386 when calling make buildworld
-) go to single-user & run the above steps
-) even did not work out in multiuser

The error in question is (which occurs after a warning):

/usr/src/lib/libc/stdlib/malloc.c: In function `arena_run_reg_alloc':
/usr/src/lib/libc/stdlib/malloc.c:1540: warning: control reaches end of 
a non-void function
*** Error code 1

Stop in /usr/src/lib/libc.
*** 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.

If needed a script-snippet is available. Actually I'm running out of 
ideas what could raise the error since line 1540 in malloc.c is an 
"assert(0);" ...

Thank you in advance,
Michael