Add override for CFLAGS and CXXFLAGS
mkdir build
cd build
+export CFLAGS="${CFLAGS} -I ${PREFIX}/include/eigen3"
+export CXXFLAGS="${CXXFLAGS} -I ${PREFIX}/include/eigen3"
+
cmake $CMAKE_ARGS -GNinja \
-DCMAKE_BUILD_TYPE:STRING=Release \
-DCMAKE_INSTALL_PREFIX:STRING=$PREFIX \
