CMake

CMake is included in the GCW Zero toolchain, as "/opt/gcw0-toolchain/usr/bin/cmake" to be exact. If you already have CMake installed systemwide, you can probably use that as well, if the versions are not too far apart.

Buildroot creates a CMake toolchain configuration file which will set several variables to the right values for cross compilation. You can use it like this:

$ cmake -DCMAKE_TOOLCHAIN_FILE=/opt/gcw0-toolchain/usr/share/buildroot/toolchainfile.cmake