The zero_bits parameter doesn't behave as expected, and some 64bit code
use it to allocate memory in the lower 32bit address space.

The expected full behaviour is:

* zero_bits == 0: no constraint on address range
* 0 < zero_bits <= 15: returned address should have as many upper bits
                       set to 0, starting at bit 31. In 64bit mode,
                       upper 32bits should all be 0 as well.
* 15 < zero_bits <= 31: unsure, but probably same as zero_bits == 15.
* zero_bits > 31: (64bit/WoW64 only) zero_bits behaves as a bitmask, as
                  if it was set to the number of leading 0 in the
                  bitmask, works in the whole 64bit range.
Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Huw Davies <huw@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>