Cross compilation error

[Neeeflix]

Hi,
currently, I am trying to use this library in a project on the Rpi. If I want to cross-compile my project, an error occurs with CMake. It says that certain files in "/usr/" are not present. If I change
if(NOT EXISTS "${file}" )
to
if(NOT EXISTS "${SYSROOT_PATH}/${file}" )
in line 63 in the generated modbuspp.cmake file, everything works fine. Would it be possible to change the CMakeLists.txt in a way that this is defined by default?