util/oslib-win32: Remove if conditional

The original ready < nhandles - 1 can be re-written as ready + 1 <
nhandles.  The check was actually incorrect because
WAIT_OBJECT_0 was not subtracted from ready; it worked because
WAIT_OBJECT_0 is zero.  After subtracting WAIT_OBJECT_0,
the result is the same condition that we are checking on the first
itteration of the for loop. This means we can remove the if statement
and let the for loop check the code.

Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Message-Id: <a14083d681951f3999a0e9314605cb706381ae8d.1498756113.git.alistair.francis@xilinx.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>