configure.ac: Remove ibosmo-sccp dependency

osmo-msc had probably forever contained a configure.ac dependency
to libosmo-sccp (that's the old static library libsccp.a), which was
only added to use a single header file (sccp_types.h).  This file
has recently been migrated to libosmo-sigtran, as libsccp.a
has been removed.

Change-Id: Ifcdad8684614c95982b6b471a5585dd42a7fb897
diff --git a/TODO-RELEASE b/TODO-RELEASE
index 0ed7189..02843d4 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -7,3 +7,4 @@
 # If any interfaces have been added since the last public release: c:r:a + 1.
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what			description / commit summary line
+libosmo-sigtran	bump dependency to > 1.9.0 / libosmo-sccp package removal