build: more accurate dependencies on Boost libraries

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

Change-Id: I9da751fe934558c753eeac0b93d7a4d505e4eb91
diff --git a/tools/wscript b/tools/wscript
index 9d198e7..63ca38b 100644
--- a/tools/wscript
+++ b/tools/wscript
@@ -7,16 +7,16 @@
         name='ndncert-client',
         target=f'{top}/bin/ndncert-client',
         source='ndncert-client.cpp',
-        use='libndn-cert')
+        use='BOOST_TOOLS libndn-cert')
 
     bld.program(
         name='ndncert-ca-server',
         target=f'{top}/bin/ndncert-ca-server',
         source='ndncert-ca-server.cpp',
-        use='libndn-cert')
+        use='BOOST_TOOLS libndn-cert')
 
     bld.program(
         name='ndncert-ca-status',
         target=f'{top}/bin/ndncert-ca-status',
         source='ndncert-ca-status.cpp',
-        use='libndn-cert')
+        use='BOOST_TOOLS libndn-cert')