Update: Optimize bitwise logic regarding removing bits.

Update: Optimize bitwise logic regarding removing bits.

I intended to eventually do this and I finally got around to it.
Change the logic to use "x &= ~y" rather than "x -= x & y" or "if (x | y) x -= y".

In the case of "x -= x & y", the resulting object code is identical in my tests.
However, the code is simpler to write with the "x &= ~y".

The "if (x | y) x -= y" results in a lot more commands in the object.