ninjabackend: drop debugging print

We don't want have this print, because it's not needed info for users.
It was introduced in cd40187d4e.

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>

ninjabackend.py

@@ -724,7 +724,6 @@ class NinjaBackend(backends.Backend):
                     extra_args.append(relname)
                 else:
                     extra_args.append(a)
-            print(extra_args)
             args += extra_args
             generated_c += [relsc]
             element = NinjaBuildElement(relsc, valac.get_language() + '_COMPILER', rel_s)