-m31 rejected when building libgcc for cross compiler for s390 (31 bit) gcc 4.6.0

["John P. Hartmann" <jphartmann@xxxxxxxxx>]

Building a cross compiler from i686 (the platform of my linux) to s390
I get the following when the bootstrap process is configuring in
s390-ibm-linux/libgcc:

configure:3268: /usr/ports/gcc390/build460/./gcc/xgcc
-B/usr/ports/gcc390/build460/./gcc/
-B/usr/ports/gcc390/inst/s390-ibm-linux/bin/
-B/usr/ports/gcc390/inst/s390-ibm-linux/lib/ -isystem
/usr/ports/gcc390/inst/s390-ibm-linux/include -isystem
/usr/ports/gcc390/inst/s390-ibm-linux/sys-include    -c -g -O2
conftest.c >&5
exec: 89: -m31: not found

I configured with:

/usr/src/gcc-4.6.0/configure --prefix=/usr/ports/gcc390/inst
--target=s390-ibm-linux --host=i686-pc-linux-gnu

However, once the directory is in the path, the bootstrap compiler
does work as far as doing

   u@ubuntu:~/src/testing$ /usr/ports/gcc390/build460/gcc/xgcc -S x.c

an even

   u@ubuntu:~/src/testing$ /usr/ports/gcc390/build460/gcc/xgcc -m31 -S x.c
   u@ubuntu:~/src/testing$ /usr/ports/gcc390/build460/gcc/xgcc -m64 -S x.c

and what is more, the two invocations generate the expected assembler
for return 0x1000000.

But the error is reproducible:

   u@ubuntu:~/src/testing$ /usr/ports/gcc390/build460/gcc/xgcc x.c
   exec: 89: -m31: not found

there is no 89 or c89 in the gcc directory.