freebsd: dlopen/dlsym/dlerror is part of libc, use LIBRARY_DL for linking

In FreeBSD there is no spearate library for dlopen, dlsym and dlerror.
Use LIBRARY_DL to check for this condition.

openbsc/src/ipaccess/Makefile.am

@@ -21,7 +21,7 @@ ipaccess_config_LDADD = $(top_builddir)/src/libbsc/libbsc.a \
 			$(top_builddir)/src/libbsc/libbsc.a \
 			$(top_builddir)/src/libtrau/libtrau.a \
 			$(top_builddir)/src/libcommon/libcommon.a \
-			-ldl -ldbi $(LIBCRYPT) $(OSMO_LIBS)
+			$(LIBRARY_DL) -ldbi $(LIBCRYPT) $(OSMO_LIBS)
 
 ipaccess_proxy_SOURCES = ipaccess-proxy.c
 ipaccess_proxy_LDADD = $(top_builddir)/src/libbsc/libbsc.a \

openbsc/src/osmo-nitb/Makefile.am

@@ -15,6 +15,6 @@ osmo_nitb_LDADD = \
 		$(top_builddir)/src/libtrau/libtrau.a \
 		$(top_builddir)/src/libctrl/libctrl.a \
 		$(top_builddir)/src/libcommon/libcommon.a \
-		-ldbi -ldl $(LIBCRYPT) 					   \
+		-ldbi $(LIBRARY_DL) $(LIBCRYPT)				   \
 		$(LIBOSMOGSM_LIBS) $(LIBOSMOVTY_LIBS) $(LIBOSMOCORE_LIBS)  \
 		$(LIBOSMOABIS_LIBS) $(LIBSMPP34_LIBS)

openbsc/tests/channel/Makefile.am

@@ -6,7 +6,7 @@ EXTRA_DIST = channel_test.ok
 noinst_PROGRAMS = channel_test
 
 channel_test_SOURCES = channel_test.c
-channel_test_LDADD = -ldl $(LIBOSMOCORE_LIBS) \
+channel_test_LDADD = $(LIBRARY_DL) $(LIBOSMOCORE_LIBS) \
 	$(top_builddir)/src/libcommon/libcommon.a \
 	$(top_builddir)/src/libbsc/libbsc.a \
 	$(top_builddir)/src/libmsc/libmsc.a -ldbi $(LIBOSMOGSM_LIBS)

openbsc/tests/db/Makefile.am

@@ -13,5 +13,5 @@ db_test_LDADD =	$(top_builddir)/src/libbsc/libbsc.a \
 		$(top_builddir)/src/libtrau/libtrau.a \
 		$(top_builddir)/src/libcommon/libcommon.a \
 		$(LIBOSMOCORE_LIBS) $(LIBOSMOABIS_LIBS) \
-		$(LIBOSMOGSM_LIBS) $(LIBSMPP34_LIBS) $(LIBOSMOVTY_LIBS) -ldl -ldbi
+		$(LIBOSMOGSM_LIBS) $(LIBSMPP34_LIBS) $(LIBOSMOVTY_LIBS) $(LIBRARY_DL) -ldbi