Buffer overrun in LsaLookupNames2() found with valgrind+wine+new heap patch

[Dan Kegel]

Here's the first error it helped Valgrind find in tonight's automated run:

../../../tools/runtest -q -P wine -M advapi32.dll -T ../../.. -p
advapi32_test.exe.so lsa.c && touch lsa.ok
...
Invalid write of size 1
   at memmove (mc_replace_strmem.c:613)
   by RtlCopySid (sec.c:376)
   by CopySid (security.c:905)
   by lookup_local_wellknown_name (security.c:2800)
   by lookup_name (lsa.c:308)
   by LsaLookupNames2 (lsa.c:411)
   by test_LsaLookupNames2 (lsa.c:336)
   by func_lsa (lsa.c:362)
 Address 0x7f03c550 is 6 bytes after a block of size 26 alloc'd
   at notify_alloc (heap.c:279)
   by RtlAllocateHeap (heap.c:1521)
   by LsaLookupNames2 (lsa.c:402)
   by test_LsaLookupNames2 (lsa.c:336)
   by func_lsa (lsa.c:362)

Offhand that looks like a real problem.  Aric, you may have touched
that code last, could you have a look?

Oh, and here's a bit that was missing from the patch.
- Dan