update notes for OSX

Author: WinterMute

README.TXT

@@ -26,19 +26,26 @@ http://www.multiprecision.org/
 sudo apt-get install libgmp-dev libmpfr-dev libmpc-dev
 
 Some of the tools for devkitARM and devkitPPC also require FreeImage, zlib,
-and libusb. Again these are built as static libraries for ease of packaging
-but you can probably use the versions supplied by your distro.
+expat, and libusb. Again these are built as static libraries for ease of
+packaging but you can probably use the versions supplied by your distro.
 
 http://freeimage.sourceforge.net/
 http://www.zlib.net
 http://www.libusb.org
+http://expat.sourceforge.net/
+
+sudo apt-get install  libfreeimage-dev zlib1g-dev libusb-dev libexpat1-dev
 
-sudo apt-get install  libfreeimage-dev zlib1g-dev libusb-dev
 
 Building gxtexconv for cube/wii needs GL/gl.h which can be obtained with
 
 sudo apt-get install mesa-common-dev
 
+For building the OSX versions we install the Xcode commandline tools and build
+pkg-config from source as well as static versions of the libraries listed above.
+This helps keep the dependencies to a minimum so end users can use the tools
+with only Xcode command line tools to obtain make.
+
 To avoid having to manually answer prompts during the build the script will
 read variables from config.sh if it exists. Copy config.sh.sample to config.sh
 and set the variables as appropriate for your build.