walproposer: move CHECK_FOR_INTERRUPTS to after waiting.

We should check it always after a sleep even before starting streaming.

pgxn/neon/walproposer.c

@@ -286,7 +286,6 @@ WalProposerPoll(WalProposer *wp)
 void
 WalProposerStart(WalProposer *wp)
 {
-
 	/* Initiate connections to all safekeeper nodes */
 	for (int i = 0; i < wp->n_safekeepers; i++)
 	{

pgxn/neon/walproposer_pg.c

@@ -1270,13 +1270,8 @@ WalSndLoop(WalProposer *wp)
 {
 	XLogRecPtr	flushPtr;
 
-	/* Clear any already-pending wakeups */
-	ResetLatch(MyLatch);
-
 	for (;;)
 	{
-		CHECK_FOR_INTERRUPTS();
-
 		XLogBroadcastWalProposer(wp);
 		WalProposerPoll(wp);
 	}
@@ -1807,6 +1802,8 @@ walprop_pg_wait_event_set(WalProposer *wp, long timeout, Safekeeper **sk, uint32
 		late_cv_trigger = ConditionVariableCancelSleep();
 #endif
 
+	CHECK_FOR_INTERRUPTS();
+
 	/*
 	 * Process config if requested. This restarts walproposer if safekeepers
 	 * list changed. Don't do that for sync-safekeepers because quite probably