[build] Don't add libgstbase twice
[build] Don't add libgstbase twice

GST_LIBS already has libgstbase (see pkg_modules), no need to add it again.

Fixes: OHB:1662

lubosz/clutter-gst,ystreet/clutter-gst,skinkie/clutter-gst,ystreet/clutter-gst,skinkie/clutter-gst,GNOME/clutter-gst,skinkie/clutter-gst,GNOME/clutter-gst,lubosz/clutter-gst,lubosz/clutter-gst,ystreet/clutter-gst,GNOME/clutter-gst,GNOME/clutter-gst,ystreet/clutter-gst