added upstream patch for getting flex buildroot package compiled with gcc7 and latest glibc.
added upstream patch for getting flex buildroot package compiled with gcc7 and latest glibc.

jens-maus/RaspberryMatic,jens-maus/RaspberryMatic,jens-maus/RaspberryMatic,jens-maus/RaspberryMatic,jens-maus/RaspberryMatic,jens-maus/RaspberryMatic