Fix the vpiObjTypeVal for signals to be scalar or vector.
Fix the vpiObjTypeVal for signals to be scalar or vector.

Scalar signals have a preferred type of vpiScalarVal, but vectors
have a preferred type of vpiVectorVal. Use the signal width to
distinguish.

CastMi/iverilog,CastMi/iverilog,CastMi/iverilog,themperek/iverilog,themperek/iverilog,themperek/iverilog