Many modules rely on the presence of other software, like the GNU Compiler Collection (aka gcc). Probably, the compiler you have isn't - er - fully compatible with the code in the state it is at the moment. It could be just a matter of compiler directives and switches (which would be luck for you), or a more serious problem that could cause you to install the new compiler.

To be on the safe side, and considering how many modules you have to install, you should jump onto GCC and get rid of many headaches. You don't say which U*ix you're working into, but I bet that you can find precompiled packages for many platforms if you don't want (or cannot) recompile it from the scratch.