build: more accurate dependencies on Boost libraries

See also named-data/ndn-cxx@5686c51b87b6a642aa2dc8d93e061caebbb226cc

Change-Id: I44f01b8dad76bf835d05f920a7943eeae3eb8c6f
diff --git a/tools/wscript b/tools/wscript
index 8fe7229..a4f1dbe 100644
--- a/tools/wscript
+++ b/tools/wscript
@@ -6,6 +6,6 @@
     for tool in bld.path.ant_glob('*.cpp'):
         name = tool.change_ext('').path_from(bld.path.get_bld())
         bld.program(name=name,
-                    target='../bin/%s' % name,
+                    target=f'{top}/bin/{name}',
                     source=[tool],
-                    use='repo-objects')
+                    use='BOOST_TOOLS repo-objects')