Take as few optional dependencies as possible, to get minimal
library bindings in Java and Python.
+NS3_HINT (empty by default)
+ Alternative path into which ns-3 should be searched for.
+
+SIMGRID_PYTHON_LIBDIR (auto-detected)
+ Where to install the Python module library. By default, it is set to the cmake Python3_SITEARCH variable if installing to /usr,
+ and a modified version of that variable if installing to another path. Just force another value if the auto-detected default
+ does not fit your setup.
+
SMPI_C_FLAGS, SMPI_CXX_FLAGS, SMPI_Fortran_FLAGS (string)
Default compiler options to use in smpicc, smpicxx, or smpiff.
This can be useful to set options like "-m32" or "-m64".