Fixed crash/reset bug of ESP8266 IGMPv2 query

Just recompiled using:
   - Arduino 1.6.13
   - esp8266-2.3.0.zip
   - Blynk-0.5.0
No source changes other than version increase to 1.0.7 at defines.h
The issue is described at esp8266/Arduino#1826

Author: bsz0206