fix $fscan("%d") for values > 32 bit
fix $fscan("%d") for values > 32 bit

The old code returns a vpiIntVal for $fscanf("%d") format strings. This
limits the maximum input range arbitrarily to 32 bit.

This patch implements %d parsing similiar to %b and %x.

'?' and 'X' chars are not accepted for %d format.

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