[1512] make sure lib/datasrc/.libs in the dyload path for python ddns tests.

this will hopefully fix distcheck failure on some systems (will check).

src/lib/python/isc/ddns/tests/Makefile.am

@@ -3,11 +3,14 @@ PYTESTS = session_tests.py
 EXTRA_DIST = $(PYTESTS)
 CLEANFILES = $(builddir)/rwtest.sqlite3.copied
 
-# If necessary, explicitly specify paths to dynamic libraries
-# required by loadable python modules.
-LIBRARY_PATH_PLACEHOLDER =
+# Specify paths to dynamic libraries required by loadable python modules.
+# We at least need to add the path to the data source backend modules.
+# Depending on system details, we may also need to specify the paths to other
+# binding modules.
 if SET_ENV_LIBRARY_PATH
-LIBRARY_PATH_PLACEHOLDER += $(ENV_LIBRARY_PATH)=$(abs_top_builddir)/src/lib/cryptolink/.libs:$(abs_top_builddir)/src/lib/dns/.libs:$(abs_top_builddir)/src/lib/dns/python/.libs:$(abs_top_builddir)/src/lib/cc/.libs:$(abs_top_builddir)/src/lib/config/.libs:$(abs_top_builddir)/src/lib/log/.libs:$(abs_top_builddir)/src/lib/util/.libs:$(abs_top_builddir)/src/lib/exceptions/.libs:$(abs_top_builddir)/src/lib/datasrc/.libs:$$$(ENV_LIBRARY_PATH)
+LIBRARY_PATH_PLACEHOLDER = $(ENV_LIBRARY_PATH)=$(abs_top_builddir)/src/lib/cryptolink/.libs:$(abs_top_builddir)/src/lib/dns/.libs:$(abs_top_builddir)/src/lib/dns/python/.libs:$(abs_top_builddir)/src/lib/cc/.libs:$(abs_top_builddir)/src/lib/config/.libs:$(abs_top_builddir)/src/lib/log/.libs:$(abs_top_builddir)/src/lib/util/.libs:$(abs_top_builddir)/src/lib/exceptions/.libs:$(abs_top_builddir)/src/lib/datasrc/.libs:$$$(ENV_LIBRARY_PATH)
+else
+LIBRARY_PATH_PLACEHOLDER = $(ENV_LIBRARY_PATH)=$(abs_top_builddir)/src/lib/datasrc/.libs:$$$(ENV_LIBRARY_PATH)
 endif
 
 # test using command-line arguments, so use check-local target instead of TESTS