VCS requires the output of the dpi calls to be of a type that can come
at the LHS of a procedural assignment, i.e. reg type. Seems to be a
different requirement from Verilator.
addResource() calls in Chisel BlackBox does not preserve order of the
files being included; the actual compile order for these files are
re-arranged to be in alphabetical order.
Therefore, while VX_gpu_pkg.sv has to be compiled before all the other
modules because it holds the top-level package definition, that order
cannot be ensured from Chisel. As a hacky workaround, simply `include
this file in some of the sv files whose name starts earlier than
VX_gpu_pkg in lexicographical order.
