Use rest_octets functionalities from libosmocore

libosmocore > 1.4.0 is required (master, not yet released) since some
fixes done in osmo-bsc code where not cherry-picked to libosmocore APIs.

Depends: libosmocore.git I2bf5635b8536b11d69774d17ac1908019633e3af
Change-Id: I7d5e5ddd174463c2a3d957c8245d2911ce013681
diff --git a/TODO-RELEASE b/TODO-RELEASE
index 6a39a21..4760012 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -9,4 +9,4 @@
 #library	what		description / commit summary line
 manual				needs common chapter cs7-config.adoc, vty_cpu_sched.adoc from osmo-gsm-manuals > 0.3.0
 osmo-bsc	Mobile Identity Coding	OsmoBSC is stricter in rejecting invalid coding of Mobile Identity IEs
-libosmocore	>1.4.0 (1.4.1?)	need BSSMAP-LE, BSSLAP, GAD coding
+libosmocore	>1.4.0 (1.4.1?)	need BSSMAP-LE, BSSLAP, GAD coding, osmo_gsm48_si*