In the above described enviroment the build of samba since version 3.0.1 fail.
The reason is a failure in the rules for the PIC-Objects in Makefile.in:
.c.@PICSUFFIX@:
...
@$(CC) -I. -I$(srcdir) $(FLAGS) @PICFLAGS@ -c $< -o $*.@PICSUFFIX@
...
The rules works for gcc, because the PICSUFFIX is po and $*.@PICSUFFIX@ is
example.po. For the Forte compiler the PICSUFFIX is po.o, because the compiler
only produce objects with suffix .o. In this case $*.@PICSUFFIX@ is
example.po.po.o. 
Very simple solution:
Change all rules with PICSUFFIX in

@$(CC) -I. -I$(srcdir) $(FLAGS) @PICFLAGS@ -c $< -o $@

I think that works for all compiler, I tested it for gcc and cc on my platform.