r8148: - make the PAC generation code a bit more readable and add some outof memory...

r8148: - make the PAC generation code a bit more readable and add some outof memory checks

- move to handmodified pull/push code for PAC_BUFFER
  to get the _ndr_size field and the subcontext size right

- after looking closely to the sample w2k3 PAC in our torture test (and some more in my archive)
  I found out that the first uint32 before the netr_SamInfo3 was also a pointer,
  (and we passed a NULL pointer there before, so I think that was the reason why the windows clients doesn't want our PAC)

  w2k3 uses this for unique pointers:

  ptr = ndr->ptr_count * 4;
  ptr |= 0x00020000;
  ndr->ptr_count;

- do one more pull/push round with the sample PAC

metze