Move vrp_set_zero_nonzero_bits from tree-vrp.c into vr-values.c, and make it use wi_set_zero_nonzero_bits.

Move vrp_set_zero_nonzero_bits from tree-vrp.c into vr-values.c, and
make it use wi_set_zero_nonzero_bits.  Remove the now redundant
wide_int_range_set_zero_nonzero_bits.

From-SVN: r277818