The github link is no longer valid and jxv (original poster) has given me these new instructions and github repo link in IRC and told me to post them here. Note that I have not tried these myself, this is just a favor for another IRC user who was having trouble:
#git clone https://github.com/slembcke/Chipmunk2D.git
#cmake -DCMAKE_TOOLCHAIN_FILE=/opt/gcw0-toolchain/usr/share/buildroot/toolchainfile.cmake -DBUILD_DEMOS=OFF -DBUILD_SHARED=OFF -DCMAKE_INSTALL_PREFIX=/opt/gcw0-toolchain/usr/mipsel-gcw0-linux-uclibc/sysroot/usr
#make
#sudo make install