When the `BT mem` operation was accessing memory where the bit offset
wasn't a multiple of the access size, then we were dividing the offset
by bytes and accessing bits at `mem[byteOffset] &= (BitOffset)`.
BitOffset wasn't adjusted to compensate for the access size being added
to the address.
Causing a mismatch of testing the wrong bits. Unit tests didn't capture
this.
Trying to run glxgears on i965/iris showed extensive corruption because
of it though.