libosmocoding: migrate transcoding routines from OsmoBTS

There are some projects, such as GR-GSM and OsmocomBB, which would
benefit from using one shared implementation of GSM 05.03 code. So,
this commit introduces a new sub-library called libosmocoding, which
(for now) provides GSM, GPRS and EDGE transcoding routines, migrated
from OsmoBTS.

The original GSM 05.03 code from OsmoBTS was relicensed under
GPLv2-or-later with permission of copyright holders (Andreas Eversberg,
Alexander Chemeris and Tom Tsou).

The following data types are currently supported:

 - xCCH
 - PDTCH (CS 1-4 and MCS 1-9)
 - TCH/FR
 - TCH/HR
 - TCH/AFS
 - RCH/AHS
 - RACH
 - SCH

Change-Id: I0c3256b87686d878e4e716d12393cad5924fdfa1
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 6d8c5d3..51050f0 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -45,6 +45,12 @@
 AT_CHECK([$abs_top_builddir/tests/conv/conv_test], [0], [expout])
 AT_CLEANUP
 
+AT_SETUP([coding])
+AT_KEYWORDS([coding])
+cat $abs_srcdir/coding/coding_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/coding/coding_test], [0], [expout])
+AT_CLEANUP
+
 AT_SETUP([msgb])
 AT_KEYWORDS([msgb])
 cat $abs_srcdir/msgb/msgb_test.ok > expout