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/libosmogsm.pc.in b/libosmogsm.pc.in
new file mode 100644
index 0000000..753bb3a
--- /dev/null
+++ b/libosmogsm.pc.in
@@ -0,0 +1,11 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: Osmocom GSM Core Library
+Description: GSM Core Library
+Version: @VERSION@
+Libs: -L${libdir} -losmogsm
+Cflags: -I${includedir}/
+