While linking pixelstruct
triangulation.cpp:(.text+0x4dc): undefined reference to __gmpn_copyi'
...
triangulation.cpp:(.text.ZN4CGALmlERKNS_4MpzfES2[ZN4CGALmlERKNS_4MpzfES2]+0xe0): undefined reference to __gmpn_mul'
Solution: Link to gmp library in src/CMakeLists