I posted yesterday about a problem I ran into in trying to get the tools to cross-compile C code to run on my first-generation Arduino Galileo. As the previous post indicates, I fixed the problem and am now able to compile C programs in a Linux environment so that they run on Clanton. I should have dug a bit deeper, though...
It turns out that it is quite possible to get the gcc compiler and tools that run on the Galileo. AlexT's Galileo and Edison Pages has a post about configuring opkg so that you can install the required packages.
When trying to install gcc, I found that I did need to pay attention to AlexT's note and use the command opkg install --force-overwrite uclibc before continuing. After installing the binutils, gcc, gcc-symlinks, and libgcc-s-dev, I can compile C programs right on the Galileo without needing to cross-compile on another platform. (As noted in my post yesterday, I boot my Galileo from an SD card using the Clanton image provided by Intel).
There are also packages available for g++.
Note (05/30/2015): The OS image for download at https://software.intel.com/en-us/iot/downloads includes development tools, but I find that image is too small (in terms of disk space) to be useful. Until I successfully build a custom image using the Yocto tools, I find it easier to use the older image (uClibc microSD card image) and add gcc.