Compiler warning about buffer overflow in firmwareVersion()

[waldhol]

I regularly compile my sketches with all compiler warnings enabled.
I got the following warning about a possible buffer overflow in WiFiClass::firmwareVersion():

/Users/***/Documents/Arduino/libraries/WiFi101/src/WiFi.cpp: In member function 'char* WiFiClass::firmwareVersion()':
/Users/***/Documents/Arduino/libraries/WiFi101/src/WiFi.cpp:356:10: note: 'sprintf' output between 6 and 12 bytes into a destination of size 9
  356 |   sprintf(_version, "%d.%d.%d", rev.u8FirmwareMajor, rev.u8FirmwareMinor, rev.u8FirmwarePatch);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The warning is legitimate.
This can be easily fixed by changing char _version[9]; to char _version[12]; in WiFi101.h

[rickoman]

Consider using 'snprintf' to prevent any overflows.