LCLS, TS 29.205: add GCR routines

Add functions to encode and decode Global Call Reference as per
3GPP TS 29.205 Table B 2.1.9.1 add corresponding tests.

Change-Id: Iee95aa4e5c056645b6cb5667e4a067097d52dfbf
Related: OS#2487
diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am
index e28ea33..ccb38ad 100644
--- a/src/gsm/Makefile.am
+++ b/src/gsm/Makefile.am
@@ -24,7 +24,7 @@
 			gsm_utils.c rsl.c gsm48.c gsm48_ie.c gsm0808.c sysinfo.c \
 			gprs_cipher_core.c gprs_rlc.c gsm0480.c abis_nm.c gsm0502.c \
 			gsm0411_utils.c gsm0411_smc.c gsm0411_smr.c gsm0414.c \
-			lapd_core.c lapdm.c kasumi.c gsm_04_08_gprs.c \
+			lapd_core.c lapdm.c kasumi.c gsm29205.c gsm_04_08_gprs.c \
 			auth_core.c auth_comp128v1.c auth_comp128v23.c \
 			auth_milenage.c milenage/aes-encblock.c gea.c \
 			milenage/aes-internal.c milenage/aes-internal-enc.c \