package/wpewebkit: select gstreamer autoaudiosink

package/wpewebkit: select gstreamer autoaudiosink

Select BR2_PACKAGE_GST1_PLUGINS_GOOD_PLUGIN_AUTODETECT when multimedia
support is enabled. This is needed at runtime to automatically select
a suitable audio output element, otherwise WebKit will crash at an
assertion due to the missing "autoaudiosink" element. More here:

  https://wpewebkit.org/about/faq.html#why-does-the-browser%2Flauncher-(e.g.-cog)-crash-when-trying-to-play-audio%3F

Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>