MacOS – compile mpich 3 with gcc 4.9 on Mavericks

As for your first question: The cleaner alternative to symlinking would be to add /Developer/usr/bin to your $PATH, so the other utilities needed for compilation can be found. That's easy to do:

export PATH=$PATH:/Developer/usr/bin

You could put that into ~/.profile so the path get set each time you open a terminal window.

And I'm certainly not a GCC/LLVM expert, but to me it seems like DevIL's configure script does expect a different version of gcc, one which doesn't expect an argument to the -V switch. My best bet would be to ask around on the DevIL developer's mailing list, as there probably are people who have been confronted with the same problem.

To get a free C/C++ compiler you have to download Xcode. It includes two C compilers; clang (the compiler Apple currently supports) and an old version of gcc. (Note current versions of Xcode >=5 I think only have clang) Make sure you install the command line tools if you want to use the compilers from outside Xcode. (These command line tools also seem to be available from Apple's developer site if you register but I would get them via Xcode unless you have a very good reason and understand the difference).

All other compilers I know of use one of these two compilers and their binary tools to set themselves up. (e.g. package management systems like macports, fink and homebrew need these command line tools to run parts of their infrastructure as well as to compiler their ports - however these package managers include ports of other c compilers e.g. newer versions of gcc.)

IDEs like Eclipse use these command line compilers to do the building of programs.

There are some commercial compilers like Intel's C++ compiler but I do not know if these require Xcode or are C compilers.