use tag for test dependency commit

Use the output of 'git describe' to pin the commit checked out
for dependency titan.ProtocolModules.SGsAP_13.2.0_commit, i.e.
the tag which points to 81544cf008378058b95ff20d33f3770fadb7e235.

Using a plain commit hash will always re-trigger an update of
the working tree in this particular case because 'git describe'
won't ever return an error.

Change-Id: Ia994b5c4488fd9b0d410b992e515c6eec4dd23b1
diff --git a/deps/Makefile b/deps/Makefile
index f2f38bd..a1ac595 100644
--- a/deps/Makefile
+++ b/deps/Makefile
@@ -78,7 +78,7 @@
 titan.ProtocolModules.RTP_commit=		R.5.A
 titan.ProtocolModules.ROSE_commit=		R.1.C
 titan.ProtocolModules.SCTP_commit=		R.2.A
-titan.ProtocolModules.SGsAP_13.2.0_commit=	81544cf008378058b95ff20d33f3770fadb7e235
+titan.ProtocolModules.SGsAP_13.2.0_commit=	R.1.B
 titan.ProtocolModules.SDP_commit=		R.14.A
 titan.ProtocolModules.SMPP_commit=		R.2.A-2-gb7aee69
 titan.ProtocolModules.SNDCP_v7.0.0_commit=	R.2.A