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/openbsc/tests/Makefile.am b/openbsc/tests/Makefile.am
index f40105f..3b1b931 100644
--- a/openbsc/tests/Makefile.am
+++ b/openbsc/tests/Makefile.am
@@ -1 +1 @@
-SUBDIRS = debug timer sms gsm0408 db channel sccp
+SUBDIRS = debug gsm0408 db channel sccp