Unitialized variable `BusOwner`

```
/home/zak/.arduino15/packages/arduino/hardware/samd/1.8.14/libraries/Wire/Wire.cpp: In member function 'virtual size_t arduino::TwoWire::requestFrom(uint8_t, size_t, bool)':
/home/zak/.arduino15/packages/arduino/hardware/samd/1.8.14/libraries/Wire/Wire.cpp:99:5: warning: 'busOwner' may be used uninitialized in this function [-Wmaybe-uninitialized]
if (!busOwner)
^~
```

Read libraries/Wire/Wire.cpp around line 99 and the surrounding TwoWire::requestFrom implementation to trace how busOwner is initialized and used. Confirm the fix with the same SAMD build that produced the warning, with no -Wmaybe-uninitialized report for this function.

Written by the indexing model from the issue text.