prefix sub-directories containing libraries with 'lib'

... and make sure tests work again after restructuring
diff --git a/openbsc/src/osmo-nitb/Makefile.am b/openbsc/src/osmo-nitb/Makefile.am
index 55822e9..44cb023 100644
--- a/openbsc/src/osmo-nitb/Makefile.am
+++ b/openbsc/src/osmo-nitb/Makefile.am
@@ -6,5 +6,9 @@
 
 osmo_nitb_SOURCES = bsc_hack.c
 osmo_nitb_LDADD = -ldl -ldbi $(LIBCRYPT) $(LIBOSMOVTY_LIBS) \
-		../bsc/libbsc.a ../msc/libmsc.a ../bsc/libbsc.a ../trau/libtrau.a ../abis/libabis.a \
-		../common/libcommon.a
+		$(top_builddir)/src/libbsc/libbsc.a \
+		$(top_builddir)/src/libmsc/libmsc.a \
+		$(top_builddir)/src/libbsc/libbsc.a \
+		$(top_builddir)/src/libtrau/libtrau.a \
+		$(top_builddir)/src/libabis/libabis.a \
+		$(top_builddir)/src/libcommon/libcommon.a