I have a script at
https://github.com/mdoege/mtmake-osx for compiling. The README has more detailed instructions.
But basically grab that repo (git clone or just download the ZIP.) Install dependencies with Homebrew: cmake, freetype, gettext, hiredis, irrlicht, jpeg, leveldb, libogg, libvorbis, luajit.
You probably don't have to install all of Xcode (it's 2 GB I think), just the Xcode commandline tools. You should get prompted to install them when you run my script.
Then run make_mac.sh from a Terminal and if everything works as intended, you should eventually get the updated compiled app in releases/. You might also have to run build_libs.sh because the existing libraries in libs/ will probably not work on your machine. Or you could comment out the line with dylibbundler in make_mac.sh, then the minetest executable will point to your libraries in /usr/local. (Dylibbundler is really only needed to make an app work on other machines which do not have the dependencies installed in /usr/local by Homebrew.)