Silence some more compiler warnings.

noisicaa/node_lib/swh/wscript

@@ -149,14 +149,11 @@ def build(ctx):
             )
             ctx.install_files(os.path.join(ctx.env.LIBDIR, bfbs.parent.path_from(ctx.bldnode)), bfbs)
 
-            cpp_env = ctx.env.derive()
-            cpp_env.append_value('INCLUDES', [os.path.join(str(ctx.path), 'src'), str(ctx.path)])
-            cpp_env.append_value('CXXFLAGS', ['-fpermissive'])
             ctx.objects(
                 target='noisicaa-node-swh-' + name,
                 source=[cpp],
-                cxxflags=['-fPIC'],
-                env=cpp_env,
+                includes=[os.path.join(str(ctx.path), 'src'), str(ctx.path)],
+                cxxflags=['-fPIC', '-fpermissive', '-Wno-unused-function'],
             )
 
     ctx.objects(