gst-plugins-bad meson: check for libsocket and libnsl
If present, add '-lsocket' and '-lnsl' to network_deps.
ext/curl/meson.build: add network_deps to dependencies gst/festival/meson.build: same sys/shm/meson.build: same
Fixes linking issues for gst-plugins-bad on Illumos distros.
This is one of the patches mentioned in Issue #848 (closed) .
I have a similar (but larger) patch against the main gstreamer project, but I wanted to start with the smaller patch in case you want adjustments made to the