problem with configure of -base from svn and libobjc2

[Sebastian Reitenbach]

Hi,

I have a problem with -base configure from svn at the stage when cheking 
whether objc really works, here the relevant part of config.log:

configure:12778: result: no
configure:12794: checking whether objc really works
configure:12824: cc -o conftest -O2 -pipe  -I/usr/local/include 
-I/usr/local/include -I/usr/local/include -I/usr/local/include  -fgnu-runtime 
-x objective-c  -L/usr/local/lib -L/usr/local/lib -L/usr/local/lib 
-L/usr/local/lib conftest.c  -lpthread -Wl,-E -shared-libgcc -fexc
eptions -fgnu-runtime -L/GNUstep/Library/Libraries -L/usr/local/lib 
-L/usr/local/lib -lobjc2 -lm     >&5
/usr/local/lib/libobjc2.so.0.0: undefined reference to 
`__sync_bool_compare_and_swap_4'
/usr/local/lib/libobjc2.so.0.0: undefined reference to `__sync_fetch_and_sub_4'
/usr/local/lib/libobjc2.so.0.0: undefined reference to `__sync_fetch_and_add_4'
/usr/local/lib/libobjc2.so.0.0: undefined reference to `__sync_add_and_fetch_4'
/usr/local/lib/libobjc2.so.0.0: undefined reference to `__sync_sub_and_fetch_4'
collect2: ld returned 1 exit status
configure:12828: $? = 1
configure: program exited with status 1
configure: failed program was:

This is on OpenBSD sparc, compiler is gcc-4.2.1. The same works well on i386, 
and macppc.
There is no problem on the sparc, when I take gnustep-base-1.23.0, instead of 
the version from svn.
libobjc2 is version 1.6.0.

anyone an idea what this could be?

Sebastian