Protect left shift from shifting too far.
Protect left shift from shifting too far.

On some systems, 1UL<<X will make a mess if X is the size of
an unsigned long. This especially seems to be a problem on i386
systems. Protect those shifts in the vvp_net.cc.
themperek/iverilog,CastMi/iverilog,themperek/iverilog,CastMi/iverilog,themperek/iverilog,CastMi/iverilog