Hey everyone,

Here's a simple patch which makes it easier to customize ffmpeg's
configure flags when inheriting from the package.

The reason I wanted to do this was so that I could enable TLS support
for ffmpeg locally. The comment in the configure flags specifies that
the tests fail with gnutls support enabled. The tests are currently
working for me with gnutls enabled, on AMD64. I'd like to send another
patch to enable it. Does anyone have any concerns about doing so?

Comments on this patch are welcomed, of course.

Thanks,

Andy