std::remove_if consolidates the non-removed elements at the start of
the vector, but it doesn't change the vector's size. After upgrading
libc++, std::remove_if is [[nodiscard]], so this bug causes a compiler
error.
Bug: 175635923
Test: m android.hardware.drm-service.castkey
Change-Id: Ie9734e616f0f93e290cd61f929af04598f236ee7