r14408: More on fix for coverity #36. The previous fix would cause us to

marshall a buffer based on an unknown size.  Zero out the sec_desc
buffer to prevent this.  This is still not getting proper results for
a registry security descriptor (everything gets ACCESS DENIED), but
at least we aren't blowing out memory now...
(This used to be commit cb370cc28ce361628df137c9aef02739aca062db)

source3/libmsrpc/cac_winreg.c

@@ -831,6 +831,8 @@ int cac_RegGetKeySecurity(CacServerHandle *hnd, TALLOC_CTX *mem_ctx, struct RegG
    uint32 buf_size;
    SEC_DESC_BUF buf;
 
+   ZERO_STRUCT(buf);
+
    if(!hnd) 
       return CAC_FAILURE;