Fix bug #7617 - smbd coredump due to uninitialized variables in the performance count...

Fix bug #7617 - smbd coredump due to uninitialized variables in the performance counter code.

In the file rpc_server.c, function _winreg_QueryValue()

uint8_t *outbuf

Should be :

uint8_t *outbuf = NULL;

As it is later freed by

      if (free_buf) SAFE_FREE(outbuf);

in some cases, this frees the unintialized outbuf, which causes a coredump.
(cherry picked from commit 84fd910c347ddfad6f01edbe7f6e25546c8382ee)
(cherry picked from commit 80e65236158d6f1690bf9f153c0eb12d81d56b8a)
(cherry picked from commit 78d1a15920de4ef3f230511257ee2f334f89a642)