finish openbsc / libosmocore separation

* use pkg-config from openbsc to find header and library
* move sms and timer tests to libosmocore itself
* ensure "make distcheck" works on both packages
diff --git a/libosmocore/configure.in b/libosmocore/configure.in
index 8c0fe67..d9fa6e8 100644
--- a/libosmocore/configure.in
+++ b/libosmocore/configure.in
@@ -34,4 +34,7 @@
 	include/osmocore/Makefile
 	include/Makefile
 	src/Makefile
+	tests/Makefile
+	tests/timer/Makefile
+	tests/sms/Makefile
 	Makefile)