gcc43 doesn't build on puredarwin, "file is not of required architecture"

[probono@…]

I am trying to build gcc43 on a i386 PureDarwin 9 system. The build starts but then runs into an error which seemingly comes from the wrong architecture being used:

...
/bin/sh ../../../../gcc-4.3.4/libgcc/../mkinstalldirs x86_64
mkdir x86_64
...
ld: warning in /usr/lib/dylib1.10.5.o, file is not of required architecture
ld: warning in /usr/lib/libc.dylib, file is not of required architecture
Undefined symbols:
  "_pthread_key_create", referenced from:
      ___gthread_key_create in unwind-dw2_s.o
...

I am attaching a full log. What can I do to enforce i386 from start to end?

[probono@…]

gcc43 build log on PureDarwin 9 i386

[probono@…]

The same error occurs when trying to build gcc44:

/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_lang_gcc44/work/build/./gcc/xgcc -B/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_lang_gcc44/work/build/./gcc/ -B/opt/local/i386-apple-darwin9/bin/ -B/opt/local/i386-apple-darwin9/lib/ -isystem /opt/local/i386-apple-darwin9/include -isystem /opt/local/i386-apple-darwin9/sys-include -g -O2 -O2  -g -O2 -DIN_GCC   -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wcast-qual -Wold-style-definition  -isystem ./include  -fPIC -pipe -g -DHAVE_GTHR_DEFAULT -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED   -I. -I. -I../.././gcc -I../../../gcc-4.4.2/libgcc -I../../../gcc-4.4.2/libgcc/. -I../../../gcc-4.4.2/libgcc/../gcc -I../../../gcc-4.4.2/libgcc/../include  -DHAVE_CC_TLS -o _fixdfdi.o -MT _fixdfdi.o -MD -MP -MF _fixdfdi.dep -DL_fixdfdi -c ../../../gcc-4.4.2/libgcc/../gcc/libgcc2.c -fvisibility=hidden -DHIDE_EXPORTS \
		-DLIBGCC2_UNITS_PER_WORD=4
ld: warning in /usr/lib/dylib1.10.5.o, file is not of required architecture
ld: warning in /usr/lib/libc.dylib, file is not of required architecture
Undefined symbols:
  "_pthread_key_create", referenced from:
      _emutls_init in emutls_s.o