Troed,
I do compile Hatari under OS X. Jerome will be the best person to answer this though. I just downloaded the latest Mercurial version this evening and I only had to add an include path for /usr/local/include to include the IPF header files since I compile Hatari with IPF support. As far as I know, it is not possible to compile Hatari without SDL support even if you use the native OS X interface, SDL is still needed as far as I know. I did not have to do anything to utils.h or utils.c. The cmake build handled almost everything for me. I am running CMake 2.8-8.
I do not compile the PNG library separately. I use the PNG library that is included in XQuartz (community-supported version of X11 when Apple dropped X11 support).
I have only been able to compile an OS X bundle. If I attempt to compile an SDL-only build, it does not work. However, I think that is a problem with my setup.
I did have problems compiling Hatari when I first installed Xcode 5. As usual, Apple changed the rules and I did not have any header files in /usr/include. I had to run a Terminal command of "xcode-select --install" in order to get the header files back where they belonged.
I do not know if this helps you or not. However, since I do compile under OS X, I did want to respond to your question.
Bob C