Well, I am not sure about the function you added, since i know not much about C++. To get gcc version, try "gcc -v" or "gcc --version" one of these (maybe both) will geve you gcc version. An advice would be try to install latest wxGTK (compile from source is the best option IMHO). The tutorial I made for compiling on solaris was made for solaris 10, but 9 *should* behave the same. I installed every package from blastwave.org, so that could be a difference. I always use self-compiled versions of wxGTK, against GTK1 (could not make it work with GTK2 IIRC) and use the webserver. Do all the files get the same error? or simply one file gets the error? is that file very big/very small/ any "interesting" feature about it? Try compiling a recent CVS version, they usually work better than 2.0.3 and have some more features.
Regards.