raatt.pas, rgobj.pas: replace some *2 loops with 'shl' or 'Bsr'.

This just replaces

l2:=1;
if (l1>=0) and (l1<=16) then
  while (l1>0) do
    begin
      l2:=2*l2;
      dec(l1);
    end;
l1:=l2;

with

if (l1>=0) and (l1<=16) then
  l1:=tcgint(1) shl l1
else
  l1:=1;

and

p:=1;
while 2*p<length do
  p:=2*p;

with

p:=longword(1) shl BsrDWord(length-1);

in attempt to look like a simplification.

Patch: 2p.patch.