This patch moves the GSM-specific functions to the new library
libosmogsm which is provided by libosmocore.

I have also moved generate_backtrace() to backtrace.c instead
of gsm_utils.c, otherwise the timer and msgfile tests depend on
libosmogsm.

Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>
diff --git a/configure.in b/configure.in
index 165cecb..b572bf4 100644
--- a/configure.in
+++ b/configure.in
@@ -101,6 +101,7 @@
 	libosmocore.pc
 	libosmocodec.pc
 	libosmovty.pc
+	libosmogsm.pc
 	include/osmocom/Makefile
 	include/osmocom/vty/Makefile
 	include/osmocom/codec/Makefile
@@ -111,6 +112,7 @@
 	src/Makefile
 	src/vty/Makefile
 	src/codec/Makefile
+	src/gsm/Makefile
 	tests/Makefile
 	tests/timer/Makefile
 	tests/sms/Makefile