LibVLC inherits nonexistent variables

libvlc_new() inherits variables from outside the core. This leads to 2 problems:

• It aborts or crashes instead of failing safe whence there are 0 modules found.
• Filters get invalid default values for their parameters:
  • In particular hardware-accelerated adjust doesn't work properly if the software adjust filter is absent.
  • The filter API generally no longer behaves as documented, e.g. the value getters return incorrect values initially.