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/tests/testsuite.at b/tests/testsuite.at
index a1cf98a..6aaaa78 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -132,6 +132,12 @@
 AT_CHECK([$abs_top_builddir/tests/gsm0808/gsm0808_test], [0], [expout], [ignore])
 AT_CLEANUP
 
+AT_SETUP([gsm29205])
+AT_KEYWORDS([gsm29205])
+cat $abs_srcdir/gsm29205/gsm29205_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/gsm29205/gsm29205_test], [0], [expout], [ignore])
+AT_CLEANUP
+
 AT_SETUP([gsm0408])
 AT_KEYWORDS([gsm0408])
 cat $abs_srcdir/gsm0408/gsm0408_test.ok > expout