Add GSM0808 utilities to Osmocore.

The code is coming from the on-waves/bsc-master branch.
diff --git a/src/Makefile.am b/src/Makefile.am
index 1697807..20e99db 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -10,7 +10,7 @@
 libosmocore_la_SOURCES = timer.c select.c signal.c msgb.c rxlev_stat.c \
 			 tlv_parser.c bitvec.c comp128.c gsm_utils.c statistics.c \
 			 write_queue.c utils.c rsl.c gsm48.c gsm48_ie.c \
-			 logging.c
+			 logging.c gsm0808.c
 
 if ENABLE_TALLOC
 libosmocore_la_SOURCES += talloc.c