For sandbox environment, the default include may be override by CPATH. To make the SCons can work in this environment, we need to pass CPATH into SCons. Change-Id: I1015f20a553a2e18595c8d2a89b209ca665879fd Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/72038 Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com> Maintainer: Jason Lowe-Power <power.jg@gmail.com>