Ok, so I changed to yaml-cpp 0.5.x (was still using 0.3.x) and got past cmake, now:
/home/build/rpmbuild/OpenColorIO/BUILD/OpenColorIO-RB-1.1/src/core/Lut1DOp.cpp:192:14: error: 'void OpenColorIO::v1::{anonymous}::Lut1D_Nearest(float*, long int, const OpenColorIO::v1::Lut1D&)' defined but not used [-Werror=unused-function]
void Lut1D_Nearest(float* rgbaBuffer, long numPixels, const Lut1D & lut)