gnustep-gui failure to build

["山口 康夫"]

I've tried to build  GWorkspace. 
But, when building gnustep-gui, gcc-mp-4.2 says, "I cannot recognize option '-weak_framework'.".
The error message is following:

gcc-mp-4.2 -fgnu-runtime -bundle -L/opt/local/lib  -flat_namespace -undefined warning -o ./GSCUPS.bundle/./GSCUPS ./obj/GSCUPSPrincipalClass.o ./obj/GSCUPSPageLayout.o ./obj/GSCUPSPrintInfo.o ./obj/GSCUPSPrintOperation.o ./obj/GSCUPSPrintPanel.o ./obj/GSCUPSPrinter.o   -L/opt/local/lib  -L../../Source/./obj   -L/opt/local/GNUstep/System/Library/Libraries/ -lcups -weak_framework Kerberos -framework CoreFoundation -framework Security -lz -lpthread -framework CoreFoundation -lgnustep-gui    -lgnustep-base     -lobjc   -lm
gcc-mp-4.2: Kerberos: No such file or directory
gcc-mp-4.2: unrecognized option '-weak_framework'
gnumake[3]: *** [GSCUPS.bundle/./GSCUPS] Error 1
gnumake[2]: *** [GSCUPS.all.bundle.variables] Error 2
gnumake[1]: *** [internal-all] Error 2
gnumake: *** [internal-all] Error 2

My system is,
PowerBook Pro G5
MacOS X 10.5 Leopard(fresh install).