Update %cvt/vr to use new double to vector conversion (constructor).
Update %cvt/vr to use new double to vector conversion (constructor).

This patch updates the %cvt/vr command to use the new double to vector
constructor. This allows the resulting bit pattern to be larger than
a long. The old method was producing incorrect results without a
warning for large bit values.

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