This fixes the bit and bif instructions.  The code is using u32
set/get, but 16/8 loop bounds, which gives out of range errors.  Also,
it is computing the value wrong, as it is a bitwise operation, not an
operation checking byte/word values for zero/non-zero.  I rewrote the
code a little to make the operation more obvious.  It now looks more
like bsl which is a closely related instruction.

The testcase fails without the patch and works with the patch.  GCC C
testsuite failures drop from 1701 to 1590 (-111).

Jim