tools/oxenstored: Fix incorrect scope after an if statement

A debug statement got inserted into a single-expression if statement.

Insert brackets to give the intended meaning, rather than the actual meaning
where the "let con = Connections..." is outside and executed unconditionally.

This results in some unnecessary ring checks for domains which otherwise have
IO credit.

Fixes: 42f0581a91 ("tools/oxenstored: Implement live update for socket connections")
Reported-by: Edwin Török <edvin.torok@citrix.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
(cherry picked from commit ee36179371)

tools/ocaml/xenstored/xenstored.ml

@@ -475,7 +475,7 @@ let _ =
 
 	let ring_scan_checker dom =
 		(* no need to scan domains already marked as for processing *)
-		if not (Domain.get_io_credit dom > 0) then
+		if not (Domain.get_io_credit dom > 0) then (
 			debug "Looking up domid %d" (Domain.get_id dom);
 			let con = Connections.find_domain cons (Domain.get_id dom) in
 			if not (Connection.has_more_work con) then (
@@ -490,7 +490,8 @@ let _ =
 					let n = 32 + 2 * (Domains.number domains) in
 					info "found lazy domain %d, credit %d" (Domain.get_id dom) n;
 					Domain.set_io_credit ~n dom
-			) in
+			)
+		) in
 
 	let last_stat_time = ref 0. in
 	let last_scan_time = ref 0. in