fix meson

Author: pcarruscag

SU2_CFD/src/meson.build

@@ -122,7 +122,6 @@ su2_cfd_src += files(['numerics/CNumerics.cpp',
                       'numerics/flow/convection/roe.cpp',
                       'numerics/flow/convection/fds.cpp',
                       'numerics/flow/convection/fvs.cpp',
-                      'numerics/flow/convection/cusp.cpp',
                       'numerics/flow/convection/hllc.cpp',
                       'numerics/flow/convection/ausm_slau.cpp',
                       'numerics/flow/convection/centered.cpp',