Fix MinGW to us _snprintf in tgt-vvp/vvp_process.c
Fix MinGW to us _snprintf in tgt-vvp/vvp_process.c

We need consistent pointer output (%p) and under MinGW we need to
us _snprintf instead of snprintf to get this. The recent event
control addition missed this. This has been reported to the MinGW
developers and they are working on a solution.

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