GPRS Cell Options (SI13): Add REL-4 CCN_ACTIVE bit

This is required in order to tell MS that osmo-pcu now supports
Network Assisted Cell Change (NACC).

Related: SYS#4909
Change-Id: I2aaa8c1107c977f711c2d7530034f57e36e3a237
diff --git a/TODO-RELEASE b/TODO-RELEASE
index 7699aff..33e27af 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -8,5 +8,6 @@
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what			description / commit summary line
 libosmogsm	new API			gsm0808_create_sapi_reject_cause() with cause argument
+libosmogsm	ABI change		struct osmo_gprs_cell_options size changed (new field at the end)
 libosmovty	ABI change		struct cmd_element: add a field for program specific attributes
 libosmovty	ABI change		struct vty_app_info: optional program specific attributes description