Fix for br970 - iverilog silently eats warnings when comma present in -W flag.
Fix for br970 - iverilog silently eats warnings when comma present in -W flag.

The -W option does not (currently) support comma separated lists and
silently ignores any string that doesn't match a known warning class.
Fix by outputing a warning message when the -W argument is unknown.

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