CLEANUP: atomic/tree-wide: replace single increments/decrements with inc/dec

This patch replaces roughly all occurrences of an HA_ATOMIC_ADD(&foo, 1)
or HA_ATOMIC_SUB(&foo, 1) with the equivalent HA_ATOMIC_INC(&foo) and
HA_ATOMIC_DEC(&foo) respectively. These are 507 changes over 45 files.
diff --git a/src/session.c b/src/session.c
index f4593ba..1038a36 100644
--- a/src/session.c
+++ b/src/session.c
@@ -50,8 +50,8 @@
 		sess->task = NULL;
 		sess->t_handshake = -1; /* handshake not done yet */
 		sess->t_idle = -1;
-		_HA_ATOMIC_ADD(&totalconn, 1);
-		_HA_ATOMIC_ADD(&jobs, 1);
+		_HA_ATOMIC_INC(&totalconn);
+		_HA_ATOMIC_INC(&jobs);
 		LIST_INIT(&sess->srv_list);
 		sess->idle_conns = 0;
 		sess->flags = SESS_FL_NONE;
@@ -90,7 +90,7 @@
 		pool_free(pool_head_sess_srv_list, srv_list);
 	}
 	pool_free(pool_head_session, sess);
-	_HA_ATOMIC_SUB(&jobs, 1);
+	_HA_ATOMIC_DEC(&jobs);
 }
 
 /* callback used from the connection/mux layer to notify that a connection is
@@ -118,7 +118,7 @@
 
 		ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_SESS_CNT);
 		if (ptr)
-			HA_ATOMIC_ADD(&stktable_data_cast(ptr, sess_cnt), 1);
+			HA_ATOMIC_INC(&stktable_data_cast(ptr, sess_cnt));
 
 		ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_SESS_RATE);
 		if (ptr)