libiconv errors bootstrapping under solaris

[Tom JONES]

I'm having problems bootstrapping gcc 3.1 on Solaris 2.7 and 8.
Here is the relevant extract from my typescript:

stage1/xgcc -Bstage1/ -B/opt/gcc31/sparc-sun-solaris2.7/bin/ -DIN_GCC    -g -O2 -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wtraditional -pedantic -Wno-long-long  -DHAVE_CONFIG_H  -o jc1 \
        java/parse.o java/class.o java/decl.o java/expr.o java/constants.o java/lang.o java/typeck.o java/except.o java/verify.o java/zextract.o java/jcf-io.o java/jcf-parse.o java/mangle.o java/mangle_name.o java/builtins.o java/jcf-write.o java/buffer.o java/check-init.o java/jcf-depend.o java/jcf-path.o java/xref.o java/boehm.o mkdeps.o main.o libbackend.a -L../zlib -lz    ../libiberty/libiberty.a
Undefined                       first referenced
 symbol                             in file
libiconv                            java/parse.o
libiconv_open                       java/parse.o
libiconv_close                      java/parse.o
ld: fatal: Symbol referencing errors. No output written to jc1
collect2: ld returned 1 exit status
gmake[2]: *** [jc1] Error 1
gmake[2]: Leaving directory `/cs/sys/src2/src/gnu/sol27_sun4.32bit/gnu/gcc-3.1/gcc'


The thing I don't understand is that the bootstrap worked fine before I 
installed GNU libiconv under /opt/gnu/lib.

Can anyone suggest how I can persuade the build to correctly link libiconv?

thanks,
Tom.