get_known_nonzero_bits_1 should use wi::bit_and_not [PR118659]

get_known_nonzero_bits_1 should use wi::bit_and_not [PR118659]

While looking into bitwise optimizations, I noticed that
get_known_nonzero_bits_1 does `bm.value () & ~bm.mask ()` which
is ok except it creates a temporary wide_int. Instead if we
use wi::bit_and_not, we can avoid the temporary and on some
targets use the andn/bic instruction.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	PR tree-optimization/118659
	* tree-ssanames.cc (get_known_nonzero_bits_1): Use
	wi::bit_and_not instead of `a & ~b`.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>