s3:smbd: Initialize struct security_ace array

s3:smbd: Initialize struct security_ace array

"Error: UNINIT (CWE-457):
samba-4.20.0rc2/source3/smbd/posix_acls.c:4599: var_decl: Declaring variable ""aces"" without initializer.
samba-4.20.0rc2/source3/smbd/posix_acls.c:4676: uninit_use_in_call: Using uninitialized value ""*aces"". Field ""aces->object"" is uninitialized when calling ""make_sec_acl"".
 4674|   	idx++;
 4675|
 4676|-> 	new_dacl = make_sec_acl(ctx,
 4677|   			NT4_ACL_REVISION,
 4678|   			idx,"

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Alexander Bokovoy <ab@samba.org>