build: more accurate dependencies on Boost libraries

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

Change-Id: I44f01b8dad76bf835d05f920a7943eeae3eb8c6f
diff --git a/tests/wscript b/tests/wscript
index 399409e..1ca51c0 100644
--- a/tests/wscript
+++ b/tests/wscript
@@ -5,16 +5,16 @@
 def build(bld):
     bld.objects(target='tests-base',
                 source=bld.path.ant_glob('*.cpp'),
-                use='repo-objects')
+                use='BOOST_TESTS repo-objects')
 
     bld.program(name='unit-tests',
-                target='../unit-tests',
+                target=f'{top}/unit-tests',
                 source=bld.path.ant_glob('unit/**/*.cpp'),
                 use='tests-base',
                 install_path=None)
 
     bld.program(name='integrated-tests',
-                target='../integrated-tests',
+                target=f'{top}/integrated-tests',
                 source=bld.path.ant_glob('integrated/**/*.cpp'),
                 use='tests-base',
                 install_path=None)