Error: lablgtk ocaml dependecies

[Daniel]

I'm trying to install the mldonkey using MacPorts 1.520 installed in a
intel mac with tiger running on it and i've got the following error
message:

--->  Building ocaml with target world.opt
Error: Target org.macports.build returned: shell command " cd
"/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_lang_ocaml/work/ocaml-3.10.0"
&& unset LD_PREBIND LD_PREBIND_ALLOW_OVERLAP && make world.opt "
returned error 2
Command output: cp byterun/ocamlrun boot/ocamlrun
cd yacc; make all
make[1]: Nothing to be done for `all'.
cp yacc/ocamlyacc boot/ocamlyacc
cd stdlib; make COMPILER=../boot/ocamlc all
make[1]: Nothing to be done for `all'.
cd stdlib; cp stdlib.cma std_exit.cmo *.cmi camlheader ../boot
if test -f boot/libcamlrun.a; then :; else \
          ln -s ../byterun/libcamlrun.a boot/libcamlrun.a; fi
if test -d stdlib/caml; then :; else \
          ln -s ../byterun stdlib/caml; fi
cd byterun; make all
make[1]: Nothing to be done for `all'.
if test -f stdlib/libcamlrun.a; then :; else \
          ln -s ../byterun/libcamlrun.a stdlib/libcamlrun.a; fi
cd yacc; make all
make[1]: Nothing to be done for `all'.
cd lex; make all
make[1]: Nothing to be done for `all'.
cd tools; make all
make[1]: Nothing to be done for `all'.
cd stdlib; make all
make[1]: Nothing to be done for `all'.
cd asmrun; make all
gcc -I../byterun -DCAML_NAME_SPACE -DNATIVE_CODE -DTARGET_i386
-DSYS_macosx  -O -Wall -D_FILE_OFFSET_BITS=64 -D_REENTRANT   -c -o
signals_asm.o signals_asm.c
signals_asm.c: In function 'segv_handler':
signals_asm.c:193: error: 'struct mcontext' has no member named '__ss'
signals_asm.c:193: error: 'struct mcontext' has no member named '__ss'
make[1]: *** [signals_asm.o] Error 1
make: *** [runtimeopt] Error 2

Error: The following dependencies failed to build: lablgtk ocaml
Error: Status 1 encountered during processing.

-------------------------------------------------------------------------------------------

I've installed Ocaml 3.10.0 before the installtion of mac ports from a
.dmg file downloaded from INRIA site and i don't know if the problem
has something to do with this prior installation.

Thank you in advance,
Daniel